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

Logic:
Find the relation between the first and second cluster in each pair based on alphabetical backward difference.

Facts & Explanation (Operation-wise):
PQ – NO: P −2 = N, Q −2 = O
KL – IJ: K −2 = I, L −2 = J
GH – EF: G −2 = E, H −2 = F
MH – IP: M −4 = I, H −7 = A (unequal / inconsistent difference)

Thus, first three pairs follow the same −2 pattern, while the last one breaks it.
Final Answer: MH – IP
Final Correct Option: (d)