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ASNT NDT Level III study materials
ASNT NDT Level III study resources

ASNT NDT Level III practice questions

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Question 1Materials, Fabrication and Product Technology

In a sand casting, where is a shrinkage cavity most likely to be found?

  1. In the last region to solidify Correct answer.
  2. Along the mold parting line
  3. Uniformly through the casting
  4. At the mold wall surface

Explanation

Shrinkage porosity forms where liquid metal cannot be fed during solidification, so it appears in the last region to freeze, usually a heavy section isolated from the riser. Its internal surface is rough and irregular, which distinguishes it from gas porosity.

Question 2Materials, Fabrication and Product Technology

Porosity in a gas tungsten arc weld is most often caused by:

  1. Moisture or grease on the joint surfaces Correct answer.
  2. Excessive welding travel speed
  3. Too low a welding current setting
  4. An arc length that is shorter than normal

Explanation

Porosity in gas tungsten arc welding usually comes from gas dissolved or entrapped in the molten pool; the common sources are moisture, grease, paint or oxide on the joint and filler, plus leaks or drafts in the shielding system. Current and arc length mainly affect fusion and bead shape rather than gas content.

Question 3Materials, Fabrication and Product Technology

Which crystal structure is typical of austenitic stainless steel at room temperature?

  1. Body-centered tetragonal
  2. Face-centered cubic Correct answer.
  3. Hexagonal close-packed
  4. Body-centered cubic

Explanation

Austenitic grades such as 304 and 316 retain a face-centered cubic lattice at room temperature, which is why they are nonmagnetic and tough. Ferritic and martensitic grades are body-centered cubic.

Question 4Materials, Fabrication and Product Technology

The heat-affected zone of a weld is best described as:

  1. Complete recrystallization to equiaxed grains
  2. Melting and rapid resolidification
  3. No change in microstructure
  4. Microstructural change without melting Correct answer.

Explanation

The heat-affected zone is base metal heated above a critical temperature but not melted, so its microstructure and properties change while its composition stays essentially the same. Because it is not remelted, it can harden, soften or lose corrosion resistance depending on the alloy.

Question 5Materials, Fabrication and Product Technology

Compared with a casting of the same alloy, a wrought product generally has:

  1. Larger grain size and greater internal porosity
  2. A higher carbon content and lower toughness
  3. Lower ductility in every direction of the product
  4. Grain orientation and fewer voids Correct answer.

Explanation

Mechanical working elongates grains into a preferred orientation, closes internal porosity and aligns inclusions, so wrought products usually have better strength and ductility than castings of the same composition. The trade-off is anisotropy, since properties differ along and across the working direction.

Question 6Materials, Fabrication and Product Technology

In a polycrystalline metal, reducing the grain size generally produces:

  1. No measurable change in mechanical properties
  2. Lower yield strength and hardness
  3. A completely amorphous structure
  4. Higher yield strength and toughness Correct answer.

Explanation

The Hall-Petch relationship shows that yield strength rises as grain size falls, because more grain boundaries obstruct slip. Finer grains also improve toughness, since a propagating crack must repeatedly change direction.

Question 7Materials, Fabrication and Product Technology

Flow lines seen on an etched section of a forged part indicate:

  1. Channels left by casting shrinkage
  2. Corrosion paths along prior austenite grains
  3. The direction of metal flow Correct answer.
  4. Networks of grain boundary carbides

Explanation

Flow lines are segregation and inclusion stringers reoriented by hot working, so they trace how the metal moved during forging. Their continuity also helps reveal laps or abrupt section changes that interrupt flow.

Question 8Materials, Fabrication and Product Technology

Brazing differs from welding in that brazing:

  1. Requires no filler metal
  2. Does not melt the base metal Correct answer.
  3. Relies on mechanical fasteners
  4. Fuses the base metal edges together

Explanation

Brazing uses a filler that melts above 450 degrees C but below the melting point of the base metal, so the joint is made by wetting and capillary action rather than by fusion of the parts. Metallurgical bonding still occurs, but without a melted base metal zone.

Question 9Materials, Fabrication and Product Technology

Hydrogen-assisted cracking in a carbon steel weldment is most likely when:

  1. High hardenability with rapid weld cooling Correct answer.
  2. The steel is low carbon and heavily preheated
  3. Post-weld heat treatment follows immediately
  4. Consumables are dried and stored properly

Explanation

Hydrogen cracking requires a susceptible hard microstructure, diffusible hydrogen and tensile stress. High hardenability combined with fast cooling produces martensite, and preheat, low-hydrogen consumables and timely post-weld heat treatment are the standard controls.

Question 10Materials, Fabrication and Product Technology

Lamellar tearing in welded steel plate is associated with:

  1. Very slow cooling of austenitic stainless steel weld metal
  2. Excessive arc voltage during the root pass
  3. Through-thickness strain around elongated inclusions Correct answer.
  4. High residual compressive stress parallel to the plate surface

Explanation

Lamellar tearing occurs when through-thickness shrinkage strain acts on plate containing flattened inclusions, opening step-like separations parallel to the rolled surface. It is most common in thick T-joints and corner joints where restraint is high.

Question 11Materials, Fabrication and Product Technology

The high solubility of hydrogen in liquid aluminium leads to which solidification defect?

  1. Hot tearing only
  2. Porosity Correct answer.
  3. Lack of penetration
  4. Slag inclusions

Explanation

Liquid aluminium dissolves far more hydrogen than the solid phase can hold, so the gas rejected during freezing collects as pores. Moisture, hydrocarbons and humid air are the usual sources of that hydrogen.

Question 12Materials, Fabrication and Product Technology

Solidification cracking of a weld is promoted by:

  1. High preheat combined with slow cooling
  2. A fine equiaxed weld grain structure
  3. A wide freezing range combined with high restraint Correct answer.
  4. Low sulfur and low phosphorus contents in the base metal

Explanation

Hot cracking occurs when a wide freezing range leaves a thin liquid film between dendrites while the joint is restrained, so the film tears as the weld contracts. Low impurities and a fine equiaxed structure resist it.

Question 13Materials, Fabrication and Product Technology

Lack of fusion in a multipass weld most often results from:

  1. Low heat input or poor interpass cleaning Correct answer.
  2. Use of an inert backing gas during welding
  3. Excessively high heat input with a wide weld pool
  4. Post-weld heat treatment at high temperature

Explanation

Lack of fusion occurs when there is too little energy to melt the sidewall or the previous bead, or when oxide or slag left on the surface prevents the arc from wetting it. Travel technique and torch angle also matter.

Question 14Materials, Fabrication and Product Technology

Sensitization of austenitic stainless steel involves:

  1. Dissolution of carbon at solution-annealing temperature
  2. Complete transformation of austenite to ferrite
  3. Chromium carbide precipitation at grain boundaries Correct answer.
  4. Sigma phase formation above 1200 degrees C

Explanation

Between roughly 425 and 815 degrees C, chromium carbides precipitate along grain boundaries and deplete the adjacent metal of chromium. Those chromium-depleted zones cannot form a passive film and become preferential paths for intergranular corrosion.

Question 15Materials, Fabrication and Product Technology

Titanium alloys require special shielding during welding because at elevated temperature they:

  1. Absorb oxygen, nitrogen and hydrogen and embrittle Correct answer.
  2. Are immune to oxidation at high temperature
  3. Melt at very low temperatures
  4. Form a protective alpha case that improves toughness

Explanation

Titanium is highly reactive when hot and readily picks up oxygen, nitrogen and hydrogen, forming hard brittle phases. Inert shielding must be maintained until the metal cools below roughly 400 degrees C.

Question 16Materials, Fabrication and Product Technology

A forging lap is best described as:

  1. An internal shrinkage void
  2. A crack running radially from the center
  3. A zone of decarburization
  4. A folded-over surface defect Correct answer.

Explanation

A lap forms when a fold of surface metal is squeezed into the workpiece during forging or rolling without being welded shut. The result is a sharp, crack-like discontinuity that acts as a stress raiser.

Question 17Materials, Fabrication and Product Technology

Chloride stress corrosion cracking of austenitic stainless steel requires:

  1. A fully austenitic structure at cryogenic temperature
  2. Compressive residual stress at low temperature
  3. Tensile stress with chlorides at elevated temperature Correct answer.
  4. Ferrite in a duplex stainless steel

Explanation

Chloride stress corrosion cracking needs a susceptible alloy, tensile stress (applied or residual) and chloride ions, usually at elevated temperature. Removing any one of those three conditions prevents cracking, which is why stress relief and chloride control are used.

Question 18Materials, Fabrication and Product Technology

In a fibre-reinforced polymer laminate, ultrasonic inspection is used mainly to find:

  1. Slag inclusions between plies
  2. Hot tears in the matrix
  3. Hydrogen flakes at the interface
  4. Delamination and porosity Correct answer.

Explanation

Laminates are built up ply by ply, so the characteristic defects are separations between plies and voids in the resin. Ultrasonic testing is well suited to these planar, interface-type discontinuities.

Question 19Materials, Fabrication and Product Technology

Quenching a medium-carbon steel and then tempering it is done to:

  1. Produce a fully austenitic structure
  2. Increase hardness while reducing toughness
  3. Relieve stress while retaining strength Correct answer.
  4. Restore the coarse cast structure

Explanation

Tempering reheats the hardened steel below the lower critical temperature, relieving quenching stresses and improving toughness at some cost in hardness. Quenching alone leaves a hard but brittle and highly stressed martensitic structure.

Question 20Materials, Fabrication and Product Technology

Placing a chill in a sand mold produces:

  1. A large shrinkage cavity at the riser
  2. A coarse columnar structure throughout the section
  3. An increase in dissolved gas porosity
  4. Local rapid solidification and a finer grain size Correct answer.

Explanation

A chill extracts heat rapidly from the adjacent metal, refining the grain structure locally and promoting directional solidification toward the riser. Chills are therefore used to prevent shrinkage porosity in heavy sections.

Question 21Materials, Fabrication and Product Technology

Reheat cracking in Cr-Mo steel weldments is caused by:

  1. Grain-boundary precipitation in the coarse-grained HAZ during PWHT Correct answer.
  2. Hydrogen diffusion after cooling to room temperature
  3. Corrosion fatigue under cyclic loading
  4. Liquid film formation at the solidification front

Explanation

During post-weld heat treatment, carbides precipitate inside coarse grains and strengthen them, so creep strain concentrates in the weaker grain boundaries, which then crack. It appears in the coarse-grained HAZ and in high-strength weld metal of creep-resistant steels.

Question 22Materials, Fabrication and Product Technology

The main inspection difficulty caused by coarse columnar grains in austenitic stainless steel welds is:

  1. Grain scattering that reduces penetrability Correct answer.
  2. Reduced attenuation and deeper penetration
  3. An effect limited to magnetic particle testing
  4. Complete transmission with no beam loss

Explanation

Large anisotropic austenite grains scatter and redirect the ultrasonic beam, producing grass-like noise and poor signal-to-noise for real defects. Lower frequency, dual-element or focused probes are often used to compensate.

Question 23Materials, Fabrication and Product Technology

Which discontinuity is characteristic of adhesive-bonded joints?

  1. Hydrogen flakes in the adhesive
  2. A zero-volume kissing bond Correct answer.
  3. Hot tearing in the adherend
  4. Slag inclusion at the bond line

Explanation

A kissing bond is an adhesion failure at the interface with essentially no gap, so conventional pulse-echo testing may show no reflection. Specialised techniques such as bond testing or high-resolution methods are needed to detect it.

Question 24Materials, Fabrication and Product Technology

Compared with gas porosity, shrinkage voids in a steel casting typically show:

  1. Perfectly spherical and smooth-walled cavities
  2. Defects confined to the casting surface
  3. Cavities filled with oxide scale
  4. Irregular interdendritic internal surfaces Correct answer.

Explanation

Shrinkage voids form between dendrites in the last areas to freeze, giving them a rough, angular internal surface in a heavy section. Gas pores are rounded and smooth because they grow as bubbles in the liquid.

Question 25Materials, Fabrication and Product Technology

Why is radiography unreliable for detecting lack of sidewall fusion in a thick butt weld?

  1. The flaw is planar and may not be imaged unless aligned Correct answer.
  2. Radiography can only be applied to magnetic materials
  3. Radiography cannot penetrate sections thicker than 25 mm
  4. Radiography is unable to reveal gas porosity in welds

Explanation

Radiography responds to changes in thickness and density, so a tight planar discontinuity shows a change in film density only when the beam lies nearly parallel to its plane. Ultrasonic testing, which responds to acoustic impedance changes, is far more reliable for planar fusion defects.

Question 26Materials, Fabrication and Product Technology

In a sand casting, the primary function of a riser is to:

  1. increase the pouring rate so that the mold fills more quickly
  2. feed molten metal into the cavity as the casting contracts Correct answer.
  3. vent dissolved and entrapped gases out of the mold cavity
  4. trap slag and other nonmetallic impurities before they enter the mold cavity

Explanation

A riser is a reservoir of liquid metal that is designed to freeze after the section it feeds, so it can supply metal that compensates solidification shrinkage. Without adequate feeding, shrinkage porosity forms in the last-freezing regions.

Question 27Materials, Fabrication and Product Technology

A carbon steel forging is normalized rather than annealed mainly to:

  1. raise the surface carbon content for improved wear resistance
  2. produce the lowest possible hardness for easier machining
  3. produce a finer, more uniform pearlitic structure Correct answer.
  4. develop a hard martensitic layer at the surface

Explanation

Normalizing cools the part in still air, which gives a finer and more uniform ferrite-pearlite structure with better toughness than the very slow furnace cooling used for annealing. Annealing, not normalizing, is chosen when the lowest possible hardness is wanted.

Question 28Materials, Fabrication and Product Technology

Seamless steel pipe is manufactured by:

  1. rotary piercing of a heated billet Correct answer.
  2. riveting together overlapping plate edges
  3. welding skelp along a longitudinal seam
  4. spiral welding of a coiled strip

Explanation

Seamless pipe is made by piercing a heated solid billet with a mandrel and then rolling or extruding it to the finished size, so the product has no seam anywhere in its circumference. Any process that joins edges produces welded, not seamless, pipe.

Question 29Materials, Fabrication and Product Technology

Sintering of a compacted powder-metal part is performed to:

  1. melt the powder completely so that it flows into the die cavity
  2. bond the particles by diffusion and raise the density Correct answer.
  3. apply a corrosion-resistant coating to the finished part
  4. burn off the admixed lubricant before compaction

Explanation

Sintering heats the compact below the melting point of the major constituent so that atoms diffuse across particle contacts, bonding the particles into a coherent body and increasing density and strength. The compacted shape must survive the cycle, so full melting is avoided.

Question 30Materials, Fabrication and Product Technology

Alternating current is normally used for TIG welding of aluminium because alternating current:

  1. prevents porosity by degassing the weld pool
  2. eliminates the need for any filler metal addition
  3. produces a more stable arc than direct current electrode negative
  4. cleans the oxide film and still gives good penetration Correct answer.

Explanation

On the electrode-positive half-cycle the arc breaks up the tenacious aluminium oxide, and on the electrode-negative half-cycle it provides good penetration with limited tungsten erosion. That combination is why AC is standard for aluminium.

Question 31Materials, Fabrication and Product Technology

A grey cast iron casting is to be repaired by arc welding. The main difficulty is that:

  1. preheating is impossible for cast irons
  2. the carbon content is too low to support an arc
  3. the graphite flakes prevent any fusion from occurring
  4. rapid cooling produces hard martensite and cracking Correct answer.

Explanation

Grey iron is high in carbon and low in ductility, so rapid cooling of the weld zone forms hard martensite while the surrounding cold iron restrains contraction, and cracking follows. Preheat and slow cooling are used to reduce this risk.

Question 32Materials, Fabrication and Product Technology

Ears form at the rim of a deep-drawn steel cup because the sheet:

  1. has a strong crystallographic texture and therefore planar anisotropy Correct answer.
  2. contains excess hydrogen from the pickling operation
  3. was drawn at too high a temperature
  4. has been over-pickled and is too thin

Explanation

Rolled sheet develops a crystallographic texture that makes flow stress direction-dependent in the plane of the sheet. During drawing the wall height varies with direction, producing the characteristic scalloped rim.

Question 33Materials, Fabrication and Product Technology

Shot peening of a finished machined component is performed to:

  1. introduce compressive residual stress that improves fatigue life Correct answer.
  2. close surface porosity by local melting
  3. increase the surface hardness while leaving residual tensile stress
  4. remove a thin layer of contaminated metal from the surface

Explanation

The impacting shot plastically stretches the surface layer, and the elastic constraint of the underlying metal leaves that layer in compression. The compressive skin opposes crack opening, so fatigue initiation and growth are retarded.

Question 34Materials, Fabrication and Product Technology

In a seawater system, carbon steel is coupled to stainless steel. Galvanic corrosion of the carbon steel is most severe when:

  1. the two areas are equal and the seawater is stagnant
  2. the seawater temperature has fallen well below 10 degrees C
  3. the stainless steel area is larger than the steel area Correct answer.
  4. the steel area is very much larger than the stainless steel area

Explanation

The corrosion rate of the anodic metal depends on the current density it must supply, which rises as the cathodic area increases. A large stainless cathode coupled to a small steel anode therefore gives the fastest loss of steel.

Question 35Materials, Fabrication and Product Technology

Compared with a low heat input pass, a high heat input pass in ferritic steel generally produces:

  1. a narrower heat-affected zone with finer grains
  2. a fully martensitic heat-affected zone throughout the joint
  3. a wider heat-affected zone with coarser grains Correct answer.
  4. no heat-affected zone at all

Explanation

Higher heat input raises peak temperature and holds it longer, so the region above the transformation temperature extends further from the fusion line and its austenite grains grow larger before transforming.

Question 36Materials, Fabrication and Product Technology

In a hand lay-up glass-fibre laminate, an excessive void content is most damaging to:

  1. the fibre volume fraction of the laminate
  2. the measured density of the finished laminate
  3. the tensile strength of the reinforcing fibres along the load axis
  4. interlaminar shear and other matrix-dominated properties Correct answer.

Explanation

Voids act as sharp discontinuities in the resin-rich regions between plies, concentrating stress where the matrix carries load. Properties controlled by the resin and the fibre-matrix interface therefore degrade far more than fibre-dominated tensile strength.

Question 37Materials, Fabrication and Product Technology

Grinding burn on a hardened steel surface indicates that:

  1. the grinding wheel was too soft for the workpiece material
  2. the wheel speed was too low and the coolant flow too high
  3. the surface has been overheated, softening it and leaving tensile stress Correct answer.
  4. the surface has been work-hardened without any heating

Explanation

Grinding burn is localised overheating, which over-tempers the martensite or rehardens it to untempered martensite. Both conditions leave tensile residual stress and can lead to cracking or reduced fatigue performance.

Question 38Materials, Fabrication and Product Technology

Chevron-shaped internal cracks (centre burst) in a cold-drawn steel bar are caused mainly by:

  1. drawing the bar at a speed well below the recommended rate
  2. excessive reduction with a high die angle, giving high centreline tension Correct answer.
  3. an excess of lubricant carried into the die and bar interface
  4. partial decarburization of the bar surface before drawing

Explanation

The deformation zone in drawing imposes a hydrostatic tensile stress on the bar axis. When reduction and die angle are large, that axial tension exceeds the ductility of the core and chevron cracks open near the centreline.

Question 39Materials, Fabrication and Product Technology

After several years of service at about 450 degrees C, a 2.25Cr-1Mo steel weldment shows a marked loss of notch toughness because:

  1. the carbides coarsen and spheroidize within the ferrite grains
  2. hydrogen diffuses back into the weld metal from the surface
  3. phosphorus and tin segregate to prior austenite grain boundaries Correct answer.
  4. graphite nodules form throughout the weld metal and heat-affected zone

Explanation

Temper embrittlement results from the segregation of trace impurities such as phosphorus, tin, antimony and arsenic to prior-austenite grain boundaries during long exposure in roughly the 350 to 550 degrees C range. Boundary cohesion drops, so the Charpy transition temperature rises.

Question 40Materials, Fabrication and Product Technology

In a dissimilar metal joint between a 2.25Cr-1Mo ferritic pipe and a 347 stainless steel nozzle, carbon migrates across the fusion line in service because:

  1. the weld metal and pipe have different electrical resistivities
  2. the chromium-rich stainless steel sets up a carbon activity gradient Correct answer.
  3. the two materials have very different thermal expansion coefficients
  4. nickel from the stainless steel diffuses into the ferritic steel

Explanation

Chromium strongly lowers carbon activity, so carbon from the ferritic steel diffuses toward the stainless side. The result is a carbide-poor, weak zone on the ferritic side and a hard, brittle carbide-rich band next to the fusion line.

Question 41Methods, Techniques and Equipment (Basic)

In radiography, the primary function of an image quality indicator (penetrameter) is to:

  1. indicate the radiographic sensitivity achieved Correct answer.
  2. verify the film processing temperature
  3. establish the required source-to-film distance
  4. measure the radiation dose at the film

Explanation

An IQI is a reference artifact whose image on the radiograph shows the smallest detail visible under the technique used, so it indicates achieved radiographic sensitivity. It is not a dosimeter, and source-to-film distance and processing temperature are controlled by other means.

Question 42Methods, Techniques and Equipment (Basic)

In a post-emulsifiable penetrant process, the emulsifier is applied to:

  1. clean the surface before penetrant application
  2. increase the fluorescence of the penetrant
  3. make the excess penetrant removable by water Correct answer.
  4. develop the indication after drying

Explanation

Post-emulsifiable penetrant is oil-based and not water-washable until an emulsifier is applied. The emulsifier combines with the surface penetrant so it can be rinsed away with water.

Question 43Methods, Techniques and Equipment (Basic)

Circular magnetization of a cylindrical part is best suited to detect discontinuities that are:

  1. randomly oriented in any direction
  2. perpendicular to the current flow direction
  3. parallel to the current flow direction Correct answer.
  4. oriented at 45 degrees to the current only

Explanation

Current flow through a part creates a circumferential magnetic field. Discontinuities that cut across the field, that is, lie parallel to the current, produce leakage flux and are detected.

Question 44Methods, Techniques and Equipment (Basic)

The main purpose of a couplant in contact ultrasonic testing is to:

  1. protect the transducer from wear
  2. provide an acoustic path between probe and part Correct answer.
  3. increase the acoustic impedance of the test part
  4. remove surface contaminants during scanning

Explanation

Air has a very low acoustic impedance, so an air gap between probe and part reflects nearly all the ultrasonic energy. Couplant fills the gap and provides a continuous acoustic path.

Question 45Methods, Techniques and Equipment (Basic)

A borescope is selected for a visual examination when:

  1. the material is at elevated temperature
  2. the indication must be recorded radiographically
  3. access is possible only through a small opening Correct answer.
  4. the surface must be measured to 0.01 mm

Explanation

A borescope is a remote visual instrument inserted through small openings to view otherwise inaccessible surfaces. It does not perform dimensional measurement, is limited by temperature, and is not a radiographic device.

Question 46Methods, Techniques and Equipment (Basic)

In eddy current testing, an increase in the electrical conductivity of a nonmagnetic test object generally causes the eddy current density to:

  1. reverse phase by 180 degrees
  2. increase Correct answer.
  3. decrease
  4. remain unchanged

Explanation

Eddy current density is proportional to conductivity because lower resistivity permits greater induced current. Higher conductivity also reduces the standard depth of penetration.

Question 47Methods, Techniques and Equipment (Basic)

The bubble immersion leak test detects leakage by:

  1. detecting ultrasonic noise produced by escaping gas
  2. bubbles escaping from a pressurized immersed object Correct answer.
  3. measuring the pressure decay in the test object
  4. monitoring the flow of tracer gas with a mass spectrometer

Explanation

In the bubble immersion test, the object is pressurized with a gas and immersed in liquid. Escaping gas forms bubbles at the leak site, which are observed visually.

Question 48Methods, Techniques and Equipment (Basic)

The three basic principles for reducing occupational radiation dose are:

  1. filtration, collimation and kilovoltage
  2. kilovoltage, current and exposure time
  3. density, contrast and sensitivity
  4. time, distance and shielding Correct answer.

Explanation

Occupational dose is reduced by minimizing exposure time, maximizing distance from the source, and interposing adequate shielding.

Question 49Methods, Techniques and Equipment (Basic)

For a straight beam contact probe, the near-field length increases when the:

  1. frequency is decreased and crystal diameter is increased
  2. frequency is decreased and crystal diameter is decreased
  3. frequency is increased and crystal diameter is increased Correct answer.
  4. frequency is increased and crystal diameter is decreased

Explanation

The near-field length is proportional to the square of crystal diameter and to frequency, so increasing both lengthens the near field.

Question 50Methods, Techniques and Equipment (Basic)

Radiographic geometric unsharpness is reduced by:

  1. increasing source size and increasing object-to-film distance
  2. decreasing source size and decreasing source-to-object distance
  3. greater source-to-object distance and less object-to-film distance Correct answer.
  4. decreasing source-to-object distance and increasing object-to-film distance

Explanation

Geometric unsharpness is proportional to source size and object-to-film distance and inversely proportional to source-to-object distance. A smaller source, greater source-to-object distance and shorter object-to-film distance reduce it.