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 lette + 8 = 3rd letter

Now, we check each options.

Option (a): LGO (Follow)

L - 5 = G, G + 8 = O

Option (b): PKS (Follow)​

P - 5 = K, K + 8 = S

Option (c): SNV (Follow)​

S - 5 = N, N + 8 = V

Option (d): UPY​​ (Not Follow)​

U - 5 = P, P + 8 $$\neq$$​ Y

Thus, correct option is (d).