If 'MANGO' is coded as 'NZOHQ', how is 'PEACH' written?

Correct — B.
Rule: shift by position: +1, −1, +1, +1, +2.

MANGO → NZOHQ:
M+1 = N, A−1 = Z (wraps back past A), N+1 = O, G+1 = H, O+2 = Q

PEACH, same steps:
P+1 = Q, E−1 = D, A+1 = B, C+1 = D, H+2 = J
→ QDBDJ, option (b).

Why the others are wrong

• (a)
  QFBDI — QFBDI moves every letter +1. Under that rule MANGO would become NBOHP, but the given code has Z second and Q last.
• (c)
  PFBID — PFBID leaves P as P, yet M → N shows the first letter moves +1, so the code must open with Q.
• (d)
  FBIDP — FBIDP opens with F. The first code letter comes from P + 1 = Q, so this fails at the first position.

Letter coding compares the word and its code position by position, using alphabet numbers (A = 1 … Z = 26).

Here the steps differ: M → N, N → O and G → H are +1, A → Z is −1, and O → Q is +2. The same list of steps, in the same order, is applied to the new word.

A step of −1 from A wraps round to Z.

Key facts

• Positions used here: A = 1, C = 3, E = 5, H = 8, M = 13, P = 16, Z = 26.
• A − 1 wraps round to Z.
• A positional code applies its step list to the new word in the same order.

Common traps

• Assuming every letter moves +1 after checking M → N alone, which gives QFBDI.
• Missing the +2 on the last letter: H + 1 = I instead of H + 2 = J.

No directly related past PYQ was found.