If CASH is coded as ECUJ, then the code for BANK will be

Start by finding the rule from CASH and ECUJ. Each letter moves two places forward in the alphabet: C to E, A to C, S to U, and H to J. So every letter is shifted by +2.

Apply the same shift to BANK. B becomes D, A becomes C, N becomes P, and K becomes M. That gives DCPM, which is option A.

Why the others fail:

• B (MCDP): B to M is a jump of 11 places, not 2. The first letter already breaks the pattern.
• C (PMCD): B to P is a jump of 14 places. The letters are right but the order and shift are wrong.
• D (PCMP): The first letter is wrong, and the code does not follow a single consistent shift.

The core concept is a uniform letter-shift code. Check the rule on every letter of the sample before you apply it, because a rule that fits only some letters is a trap. This is a Reasoning item, and it trains the same discipline you need for series and analogy questions in the CSAT section.

Trap: Aspirants often spot the shift on one or two letters and assume it holds for all, or they count backwards from the wrong end of the alphabet.