The verified answer to “In a certain code, CROP is written as QPSD. How will TRAIN be written in that code?” is OJBSU, option C. The source working states: Correct answer: OJBSU (Option D). Apply the same unchanged rule to TRAIN: T→O, R→J, A→B, I→S, N→U. Therefore the required code is OJBSU. Wrong options: USBJO is wrong because it does not reproduce the verified rule at every position; VTCKP is wrong because it does not reproduce the verified rule at every position; SQZHM is wrong because it does not reproduce the verified rule at every position. Even one mismatched position invalidates a code, so only Option D is correct. This observation must be confirmed across every available letter position or every consecutive term before it is applied to the missing code. Applying the verified rule to the target expression produces OJBSU. The alternatives VTCKP, SQZHM and USBJO fail because at least one position does not obey the same transformation. A useful final check is to map OJBSU backward through the inverse operation and confirm that the original target is recovered.