The verified answer to “In a certain code, PORT is written as USPQ. How will RIVER be written in that code?” is SFWJS, option C. The source working states: Correct answer: SFWJS (Option D). Apply the same unchanged rule to RIVER: R→S, I→F, V→W, E→J, R→S. Therefore the required code is SFWJS. Wrong options: SJWFS is wrong because it does not reproduce the verified rule at every position; TKXGT is wrong because it does not reproduce the verified rule at every position; QHUDQ 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 SFWJS. The alternatives TKXGT, QHUDQ and SJWFS fail because at least one position does not obey the same transformation. A useful final check is to map SFWJS backward through the inverse operation and confirm that the original target is recovered.