If LEMON is coded as KDNLN, how is MANGO written?

Correct — A.
Rule: copy each position's shift. LEMON → KDNLN moves the letters −1, −1, +1, −3, 0.

L → K (−1), E → D (−1), M → N (+1)
O → L (−3), N → N (0)

MANGO: M → L, A → Z (A − 1 wraps round to Z), N → O
G → D, O → O

= LZODO → option (a).

Why the others are wrong

• (b)
  LZLFP — LZLFP moves N back 2 to L, but the third shift is +1, so N becomes O. G − 3 is D, not F.
• (c)
  LZMFQ — LZMFQ takes the third letter N back to M. The third shift is +1, giving O, and the last letter stays O, not Q.
• (d)
  LZLFO — LZLFO gets the last letter right, but N + 1 is O, not L, and G − 3 is D, not F.

Letter coding compares the word with its code one position at a time. Write each letter's alphabet position, then the shift: L (12) → K (11) is −1, O (15) → L (12) is −3.

The shifts here follow no progression, so there is nothing to predict. The code is fixed by position: the first letter moves −1, the fourth −3, the fifth not at all.

Key facts

• A − 1 wraps round to Z, and Z + 1 wraps round to A.
• L = 12, O = 15, G = 7, D = 4 in alphabet positions.
• A position-wise code applies the same shift to the same position of any word of that length.

Common traps

• Missing the wrap from A back to Z
• Assuming every position moves −1 because the first two letters do

No directly related past PYQ was found.