The verified answer to “In a certain code, PATH is written as APHT. The source working states: Correct answer: IRGN (Option B). Apply the same unchanged rule to RING: R→I, I→R, N→G, G→N. Therefore the required code is IRGN. Wrong options: SJOH is wrong because it does not reproduce the verified rule at every position; TKPI is wrong because it does not reproduce the verified rule at every position; QHMF is wrong because it does not reproduce the verified rule at every position. Even one mismatched position invalidates a code, so only Option B 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 IRGN. The alternatives TKPI, QHMF and SJOH fail because at least one position does not obey the same transformation. A useful final check is to map IRGN backward through the inverse operation and confirm that the original target is recovered.