Letter series completion: BCFG, JKNO, RSVW, what comes next? Choose the group of four letters that logically follows the given pattern.

Introduction / Context:
This question tests recognition of alphabetic letter-series patterns where each term is a 4-letter block following a consistent intra-block rule and a consistent jump between blocks. Spotting both the within-block spacing and the block-to-block progression is essential for accuracy.

Given Data / Assumptions:

• Series: BCFG, JKNO, RSVW, ?
• We assume standard English alphabet order with wrap-around allowed (Z to A) if required.

Concept / Approach:
The key is to analyze (1) the pattern inside each 4-letter block and (2) how the blocks progress. Within every block, the letter jumps follow +1, +3, +1. Between blocks, the starting letter advances by a fixed step across blocks.

Step-by-Step Solution:
1) Inspect block 1 (BCFG): B->C = +1, C->F = +3, F->G = +1. So inside-block rule: +1, +3, +1.2) Check block 2 (JKNO): J->K = +1, K->N = +3, N->O = +1. The same rule holds.3) Check block 3 (RSVW): R->S = +1, S->V = +3, V->W = +1. Again, the rule holds.4) Determine starting letters across blocks: B (2), J (10), R (18). Each step is +8. Next start = 18 + 8 = 26 => Z.5) Apply inside-block rule from Z with wrap-around: Z +1 = A; A +3 = D; D +1 = E.6) Thus the next block is Z A D E.

Verification / Alternative check:
Confirm the +8 jump in starts continues B→J→R→Z and the inside-block +1, +3, +1 applies uniformly, including Z→A wrap-around. Both checks pass, so ZADE is validated.

Why Other Options Are Wrong:

• HIKL: Does not continue the +8 starting-letter jump from R.
• STUX: Starts at S (+1 from R), not +8, and violates the intra-block spacing.
• MNPQ: Starts at M (−4 from R), not +8; internal steps don’t match +1, +3, +1.

Common Pitfalls:
Candidates often spot only the internal +1, +3, +1 but miss the +8 jump between starting letters, or vice versa. Others forget alphabet wrap-around when moving past Z. Always test both dimensions of the pattern and consider modular wrap-around.

Final Answer:
ZADE