Three of the following four letter-clusters are alike in a certain way and thus form a group. Which is the letter-cluster that does NOT belong to that group?
(Note: The odd one out is not based on the number of consonants/vowels or their positions in the letter-cluster.)​​

Logic: 1st letter + 10 = 2nd letter and 2nd letter + 10 = 3rd letter

Now, we check each options.

Option (a): ISC (Follow)

I + 10 = S, S + 10 = C

Option (b): LEO (Not Follow)​

IL + 10 $$\neq$$​ E, E + 10 = O

Option (c): PZJ (Follow)​

P + 10 = Z, Z + 10 = J

Option (d): OYI (Follow)​

O + 10 = Y, Y + 10 = I

Thus, correct option is (b).