Based on English alphabetical order, three of the following four…

In an alphabet-classification question, each letter is replaced by its position in the English alphabet (A = 1, B = 2, ... Z = 26). Three of the four letter-clusters share one consistent step pattern between consecutive letters, and those three form the group; the cluster whose step pattern differs from that shared rule is the one that does not belong.

Convert every cluster to alphabet positions and note the step from the 1st letter to the 2nd, and from the 2nd letter to the 3rd:

XYV, OPM, and FGD all step +1 and then -3 between their letters, so they follow the identical rule and form the group. WYU steps +2 and then -4, a different step pattern, so WYU is the letter-cluster that does not belong.

Cross-check: comparing only the 1st and 3rd letters gives a -2 net shift in all four clusters (X to V, O to M, F to D, and even W to U), so checking endpoints alone is misleading here. The defining rule is the exact two-step sequence (+1, then -3) shared by three clusters, not just the net displacement, which confirms WYU as the genuine outlier.