The verified answer to “In a certain code, NOTE is written as QRWH. How will BRAIN be written in that code?” is EUDLQ, option D. The source working states: Correct answer: EUDLQ (Option A). Apply the same unchanged rule to BRAIN: B→E, R→U, A→D, I→L, N→Q. Therefore the required code is EUDLQ. Wrong options: CSBJO is wrong because it does not reproduce the verified rule at every position; DTCKP is wrong because it does not reproduce the verified rule at every position; AQZHM 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 EUDLQ. The alternatives CSBJO, DTCKP and AQZHM fail because at least one position does not obey the same transformation. A useful final check is to map EUDLQ backward through the inverse operation and confirm that the original target is recovered.