Based on the position in the English alphabetical order, three of the following letter clusters are alike in some manner and one is different

Based on the position in the English alphabetical order, three of the following letter clusters are alike in some manner and one is different. Select the odd letter-cluster.

A.            QUXZ

B.            GKOQ

C.            AEIK

D.            KOSU

Sol:

Pattern follows here is +4, +4, +2