In the questions given below, select the one which is different from the other three responses.

Logic: 1st letter + 2 = 2nd letter and 2nd letter + 3 = 3rd letter

Now, we check each options.

Option (a): ACF

A + 2 = C, C + 3 = F

Option (b): EGI

E + 2 = G, G + 3 = J $$\neq$$ I​

Option (c): IKN

I + 2 = K, K + 3 = N

Option (d): MOR​​

M + 2 = O, O + 3 = R

So, EGI is odd one out.

Thus, correct option is (b).