Four letter-cluster have been given out of which three are alike in some manner, while one is different. Choose the odd one.

We know that A=1, B=2, C=3, D=4 ....... Z=26

then from the above option (B) IKMO (C)CEGI (D) TVXZ

the above follow the same pattern given below 

the check option represents in the form of alphabet position 

(B)  9 11 13 15  every alphabet difference between two (2) positions.

(C)3 5 7 9  every alphabet difference between two (2) positions.

(D)20 22 24 16  every alphabet difference between two (2) positions.

but option (A) does not follow the difference two-position alphabet

(A) OQRT represent in the form of alphabet position 15 17 18 20 it difference between 2,1 ,2

therefore option (A) OQRT Ans