Letter-ordering (forms a meaningful English word): Given letters with fixed positions — X(1) O(2) M(3) L(4) C(5) P(6) E(7) — which index sequence produces a valid word?

Introduction / Context:
Pick an index sequence to form a known English word from the fixed sequence X(1), O(2), M(3), L(4), C(5), P(6), E(7).

Given Data / Assumptions:

• Indices map 1→X, 2→O, 3→M, 4→L, 5→C, 6→P, 7→E.

Concept / Approach:
The natural target is “COMPLEX.”

Step-by-Step Solution:
Option D: 5,2,3,6,4,7,1 → C, O, M, P, L, E, X = “COMPLEX”.

Verification / Alternative check:
Compare letters and positions; all letters used once; spelling correct.

Why Other Options Are Wrong:
They yield non-words or misordered strings.

Common Pitfalls:
Swapping PX or ending on E instead of X.

Final Answer:
5, 2, 3, 6, 4, 7, 1