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.)

From the given options-

A: D T I
D + 5 = I

I + 11 = T
B: A Q G 
A + 6 = G

G + 10 = Q
C: H X N 
H  + 6 = N

N + 10 = X 
D: S I Y 
S + 6 = Y

Y + 10 = I
a) DTI is the odd one out because it follows +5, +11.
Correct answer is (A)