Based on the English alphabetical order, three of the following four letter-cluster pairs are alike in a certain way and thus form a group. Which letter-cluster pair 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)

Correct option is D

Given:
QR – WX, LM – RS, ST – YZ, GH – OM

Logic:

In each pair, both letters of the second cluster are formed by adding +6 alphabetically to the letters of the first cluster — except one pair which does not follow this pattern.

Explanation (applied left to right):
Q +6 = W, R +6 = X → follows rule
L +6 = R, M +6 = S → follows rule
S +6 = Y, T +6 = Z → follows rule
G +8 = O, H +5 = M → does not follow rule

Final Answer:
GH – OM

Final Correct Option:
(d) GH – OM