Which letter-number cluster should replace the question mark in the series so…

Concept

In an alpha-numeric series, inspect each letter position and the numeric part as separate sequences.

Apply the same fixed change from one term to the next; when a letter passes Z, continue again from A.

Application

1. From XJT22 to ZLV43, each letter advances by 2 positions and the number increases by 21.

2. The same changes produce BNX64 and then DPZ85; the wrap from Z to B still represents an advance of 2 positions.

3. Applying the rule to DPZ85 gives D→F, P→R, Z→B, and 85+21=106.

Cross-check

Reading each column independently gives X, Z, B, D, F; J, L, N, P, R; T, V, X, Z, B; and 22, 43, 64, 85, 106. All four columns follow a constant step.

Therefore, the missing cluster is FRB106.