Progressive alphabet groups – choose the correct 4-letter block: A, CD, GHI, ?, UVWXY

Introduction / Context:
This pattern builds groups of letters whose lengths increase by 1 each time (1, 2, 3, 4, 5 …). The starting letter of each group also advances by a steadily growing step. Identifying both features leads to the correct four-letter block.

Given Data / Assumptions:

• Groups: A | CD | GHI | ? | UVWXY.
• Group lengths: 1, 2, 3, 4, 5.

Concept / Approach:
Find the starting letter of each group and measure how far it jumps from the previous group’s start. Many reasoning sets use differences that rise by +2, then +4, then +6, etc. Here we will see a +2, +4, +6, +8 progression for starting letters.

Step-by-Step Solution:
Start letters: A(1), C(3), G(7), ?, U(21).Gaps between starts: A→C = +2; C→G = +4; therefore the next gap should be +6: 7 + 6 = 13 = M.The 4-letter group starting at M should be M, N, O, P (four consecutive letters).Finally, the next start U(21) is +8 from M(13), confirming the +2, +4, +6, +8 pattern.

Verification / Alternative check:
Check lengths: 1, 2, 3, 4, 5; check starts: 1, 3, 7, 13, 21. Differences 2, 4, 6, 8 affirm the intended arithmetic progression and validate MNOP as the required block.

Why Other Options Are Wrong:

• LMNO starts at L, which would imply a +5 step, breaking the +2, +4, +6 rule.
• MNO has only 3 letters; NOPQ starts correctly but shifts the start forward by +7.

Common Pitfalls:

• Focusing only on group length and ignoring how far the starting letter advances between groups.

Final Answer:
MNOP