The verified answer to “In a certain code, PLAY is written as RNCA. The source working states: Correct answer: GCTVJ (Option B). Apply the same unchanged rule to EARTH: E→G, A→C, R→T, T→V, H→J. Therefore the required code is GCTVJ. Wrong options: FBSUI is wrong because it does not reproduce the verified rule at every position; DZQSG is wrong because it does not reproduce the verified rule at every position; CYPRF 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 GCTVJ. The alternatives DZQSG, CYPRF and FBSUI fail because at least one position does not obey the same transformation. A useful final check is to map GCTVJ backward through the inverse operation and confirm that the original target is recovered.