Pick the odd man out.

Key idea: in most groups the consecutive letters increase by the same number of positions in the alphabet; the odd group does not.

• AEK: A = 1, E = 5, K = 11 → differences +4 and +6. Differences are not equal, so this group is the odd one out.

• DFH: D = 4, F = 6, H = 8 → differences +2 and +2. Equal increments, so this group is not odd.

• TWZ: T = 20, W = 23, Z = 26 → differences +3 and +3. Equal increments, so this group is not odd.

• MOQ: M = 13, O = 15, Q = 17 → differences +2 and +2. Equal increments, so this group is not odd.

Conclusion: AEK is the odd one out because its consecutive letter differences (+4 and +6) are not equal, whereas the other groups have equal-step progressions.