Odd man out.

Concept: In an alphabet-based “odd one out” series, convert each letter to its position in the alphabet (A = 1 ... Z = 26) and compute the same relationship for every pair — here, the numerical difference between the two letters' positions. The pairs that share one kind of value (e.g. an odd difference) follow the group's pattern; the pair whose relationship differs is the odd one out.

Application:

1. Assign position values: X = 24, M = 13; H = 8, U = 21; Z = 26, Y = 25; Z = 26, V = 22.

2. Find the difference within each pair: XM → 24 - 13 = 11; HU → 21 - 8 = 13; ZY → 26 - 25 = 1; ZV → 26 - 22 = 4.

3. Classify each difference as odd or even: 11 is odd, 13 is odd, 1 is odd, 4 is even.

4. Three pairs (XM, HU, ZY) share an odd difference; one pair (ZV) has an even difference, breaking the shared pattern.

Cross-check: Recomputing ZV's difference independently (26 - 22 = 4) confirms it does not fit the odd-parity rule established by the other three pairs.

Result: ZV is the odd one out.