Which letter cluster should replace the question mark (?) in the following…

Concept

In a letter-cluster series, compare corresponding letters by their alphabet positions (A = 1 to Z = 26). If every letter advances by the same number k, the next cluster follows that constant shift; after Z, counting wraps back to A.

Application

1. From NIOG to VQWO: N→V, I→Q, O→W, and G→O are each shifts of +8.

2. From VQWO to DYEW: V→D, Q→Y, W→E, and O→W are again +8, using wrap-around after Z where needed.

3. From DYEW to LGME: D→L, Y→G, E→M, and W→E are also +8, so the same rule holds across all given transitions.

4. Apply +8 to LGME: L→T, G→O, M→U, and E→M. Reading the results in order gives TOUM.

Cross-check

• The shift vector from LGME to TOUM is (+8, +8, +8, +8).

• For TUHG, THGV, and TOIL, the four corresponding shifts are not all equal, so those clusters do not continue the established constant-shift pattern.

Result

Therefore, the missing letter cluster is TOUM.