Each defect in Column I is named after or closely tied to the process where it is most commonly seen, so the fast route is recalling the process linked to each defect name and checking it against the four options.
(A) P-3, Q-4, R-2, S-1: Flashline cracking is placed under Extrusion, but flash is a forging term, since closed-die forging is what produces a parting-line flash, not extrusion. Wrong.
(B) P-4, Q-3, R-1, S-2: Edge cracking is placed under Extrusion and cracked core under Forging, and neither fits, since edge cracking is a rolling defect and cracked core is a casting defect. Wrong.
(C) P-4, Q-2, R-3, S-1: Edge cracking under Extrusion is wrong, since edge cracking is tied to width-wise flow during rolling, not extrusion. Wrong.
(D) P-3, Q-2, R-4, S-1: Edge cracking under Rolling, flashline cracking under Forging, chevron cracking under Extrusion, cracked core under Casting. Each defect sits with the process it is actually named for and observed in. Correct.
Option (D) is the only self-consistent set.
Let's summarize:
Edge cracking: rolling, from uneven strip-edge deformation.
Flashline cracking: forging, along the die parting line.
Chevron cracking: extrusion, an internal centerline defect.
Cracked core: casting, from a failed sand or metal core.
So the correct match is P-3, Q-2, R-4, S-1, option (D).
