Find the preimage under a constant +4 shift: LKJ : pon :: ? : hgf

Introduction / Context:
This coding-decoding item uses a constant forward shift across letters. We are given the output and must infer the input by reversing the shift. Such inverse reasoning is routine in alphabet mapping questions.

Given Data / Assumptions:

• LKJ maps to pon with a +4 shift (L→p, K→o, J→n).
• We need a word that maps to hgf via the same +4 rule.
• Case is not semantically important; letter identities are.

Concept / Approach:
If output = input shifted by +4, then input = output shifted by −4. Compute each letter accordingly using alphabet positions with wrap-around as needed.

Step-by-Step Solution:

Verification / Alternative check:
Reapply the forward rule on DCB to see if you recover hgf. The mapping is exact and uniform, so the verification succeeds immediately.

Why Other Options Are Wrong:

• dcle/DBC/dcd: Each contains at least one letter that fails the strict −4 back-shift from h, g, f.

Common Pitfalls:
Miscounting by one step or swapping direction (+4 vs −4). Always compute carefully and maintain consistency across all positions.

Final Answer:
DCB