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.)​

Correct option is A

Logic = first letter - 2 = second letter and second letter + 4 = third letter
(A) POR
P - 2 = N not O
O + 4 = S not R
Different from the others
(B) SQU
S - 2 = Q
Q + 4 = U
Pattern: –2, +4
(C) LJN
L - 2= J
J + 4 = N
Pattern: –2, +4
(D) ECG
E -2 = C
C + 4 = G
Pattern: –2, +4
Final Correct Option: (A) POR