The verified answer to “In a certain code, STAR is written as TSBQ. How will WATER be written in that code?” is XZUDS, option D. The source working states: Correct answer: XZUDS (Option A). Apply the same unchanged rule to WATER: W→X, A→Z, T→U, E→D, R→S. Therefore the required code is XZUDS. Wrong options: XBUFS is wrong because it does not reproduce the verified rule at every position; YCVGT is wrong because it does not reproduce the verified rule at every position; VZSDQ is wrong because it does not reproduce the verified rule at every position. Even one mismatched position invalidates a code, so only Option A 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 XZUDS. The alternatives XBUFS, YCVGT and VZSDQ fail because at least one position does not obey the same transformation. A useful final check is to map XZUDS backward through the inverse operation and confirm that the original target is recovered.