Three of the following four letter-clusters are alike in a certain way and one is different. Pick the odd one out

Three of the following four letter-clusters are alike in a certain way and one is different. Pick the odd one out.

A.            TQR

B.            MJK

C.            IFG

D.            NKI

Sol:

Except option D, Pattern follows here is: – 3, +1.