Fill the missing group: A, CD, GHI, ( ? ), UVWXY. Group lengths grow 1, 2, 3, 4, 5; starting letters advance by +2, +4, +6, +8: A → C → G → M → U.

Introduction / Context:
The pattern involves two controls: the number of letters per group and the starting letter progression.

Given Data / Assumptions:

• Groups: 1, 2, 3, 4, 5 letters respectively.
• Starting letters: A, C, G, M, U with jumps +2, +4, +6, +8.

Concept / Approach:
Determine the correct starting letter for the 4-letter group and then list 4 consecutive letters.

Step-by-Step Solution:

Verification / Alternative check:
Counting letters per group (1→2→3→4→5) matches A / CD / GHI / MNOP / UVWXY.

Why Other Options Are Wrong:
LMNO starts at L, not M; MNO has only 3 letters; NOPQ starts at N, not M.

Common Pitfalls:
Focusing only on group length and missing the non-linear jumps in starting letters.

Final Answer:
MNOP.