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 + 3 = 2nd letter, 2nd letter - 6 = 3rd letter

Option (a): LOI

L + 3 = O, O - 6 = I

Option (b): PSM

P + 3 = S, S - 6 = M

Option (c): RUO

R + 3 = U, U - 6 = O

Option (d): TWS

T + 3 = W, W - 6 = Q ≠ S,

There are three options A, B, C which are following the same logic.

So, TWS is the odd one out.

Thus, the correct option is (d) TWS