In a certain code language, 'NAME’ is written as 'FNBO' and 'NANO' is written as 'POBO’. How will 'NAIL’ be written in that language?

Correct — D. Two steps, applied in this order.

Rule: shift every letter one place forward, then write the result backwards.

NAME → OBNF → backwards → FNBO, the code the question gives.
NANO → OBOP → backwards → POBO, which the question also confirms.

NAIL → OBJM → backwards → MJBO → option (d)

Why the others are wrong

• (a)
  MOBJ — MOBJ is OBJM with the last letter moved to the front, not the string reversed. Reversing OBJM gives M, J, B, O.
• (b)
  MJOB — MJOB swaps the final two letters of the answer. After the reversal the order is M, J, B, O, so B comes third.
• (c)
  MOJB — MOJB puts O in second place. The second letter of the reversed string has to be J, because J is second from the end of OBJM.

A coding question with two sample words is asking you to find a single procedure that reproduces both codes.

Compare the code with the word letter by letter first. Here N, A, M, E and F, N, B, O share no obvious position-by-position link, which is the signal to try a reversal.

Once you suspect a reversal, undo it: read FNBO backwards to get OBNF, set it under NAME, and the +1 shift is immediate.

Key facts

• NAME shifted forward one letter is OBNF, and OBNF reversed is FNBO.
• NANO shifted forward one letter is OBOP, and OBOP reversed is POBO.
• N, A, I and L shift to O, B, J and M.

Common traps

• Pairing the letters position by position, N with F and A with N, instead of testing a reversal
• Shifting the letters correctly and then forgetting to reverse
• Shifting backwards by one because the code letter F sits before the word's letters

No directly related past PYQ was found.