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 is the one that 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)

Let's analyze the positional shifts of letters in each pair based on the English alphabet:

• OG – ML: First letter O (15) to M (13) is a shift of -2. Second letter G (7) to L (12) is a shift of +5.
• GA – EF: First letter G (7) to E (5) is a shift of -2. Second letter A (1) to F (6) is a shift of +5.
• KQ - IV: First letter K (11) to I (9) is a shift of -2. Second letter Q (17) to V (22) is a shift of +5.
• CW - ZB: First letter C (3) to Z (26) is a shift of -3 (C $\to$ B $\to$ A $\to$ Z). Second letter W (23) to B (2) is a shift of +5 (W $\to$ X $\to$ Y $\to$ Z $\to$ A $\to$ B).

The common pattern for the first three pairs is a -2 shift for the first letter and a +5 shift for the second. The pair CW - ZB is the odd one out as its first letter undergoes a -3 shift.