Based on the English alphabetical order, three of the following four letter-clusters are alike in a certain way and thus form a group. Which letter-cluster DOES NOT belong to that group?
(Note: The odd one out is not based on the number of consonants/vowels or their position in the letter-cluster.)

Logic: 1st letter - 5 = 2nd letter and 2nd letter + 4 = 3rd letter

Now, we check each options.

Option (a): FAE (Follow)

F - 5 = A, A + 4 = E

Option (b): NIM (Follow)​

N - 5 = I, I + 4 = N

Option (c): KFI (Not Follow)​

K - 5 = F, F + 4 $$\neq$$ I​

Option (d): GBF (Follow)​

G - 5 = B, B + 4 = F

Thus, correct option is (c).