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 man out is not based on the number of consonants/vowels or their position in the letter-cluster.)

Logic: 1st letters - 10 = 2nd letters, 2nd letters + 16 = 3rd letters.

Option (a): KAQ

K - 10 = A, A + 16 = Q

Option (b): RHX

R - 10 = H, H + 16 = X

Option (c): WMC

W - 10 = M, M + 16 = C

Option (d): QEU

Q - 12 = E, E + 15 = U

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

So, the correct odd one out is QEU.

Thus, the correct option is (d) QEU.