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 + 7 = 2nd letter and 2nd letter - 4 = 3rd letter

Now, we check each options.

Option (a): ELH (Follow)

E + 7 = L, L - 4 = H

Option (b): JQM (Follow)​

J + 7 = Q, Q - 4 = M

Option (c): GNI (Not Follow)​

G + 7 = N, N - 4 $$\neq$$​ I

Option (d): LSO (Follow)​

L + 7 = S, S - 4 = O

Thus, correct option is (c).