Four terms have been given in options, out of which three are alike in some manner and one is different. Select the odd one.

Let's analyze all the options:

Logic: Number denote the place value of 1st letter and The second letter is the opposite of the first letter in the alphabet.

(a) 9IH – (I’s opposite should be R, not H)
(b) 11KP –  (K’s opposite is P)
(c) 13MN –  (M’s opposite is N)
(d) 3CX –  (C’s opposite is X)

Odd One Out: (a) 9IH

Thus, the correct option is (a) 9IH