The verified answer to “In a certain code, ROOM is written as PMMK. How will HEART be written in that code?” is FCYPR, option C. The source working states: Correct answer: FCYPR (Option D). Apply the same unchanged rule to HEART: H→F, E→C, A→Y, R→P, T→R. Therefore the required code is FCYPR. Wrong options: IFBSU is wrong because it does not reproduce the verified rule at every position; JGCTV is wrong because it does not reproduce the verified rule at every position; GDZQS 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 FCYPR. The alternatives JGCTV, GDZQS and IFBSU fail because at least one position does not obey the same transformation. A useful final check is to map FCYPR backward through the inverse operation and confirm that the original target is recovered.