Directions: Select the option that is related to the third letter-pair in the same way as the second letter-pair is related to the first letter-pair.

GH : EF :: CD : ?

The correct option is AB.

Step-by-step explanation:

1. Analyze the relationship between the first pair of letters, GH, and the second pair, EF:
- First letter: G is the 7^th letter of the alphabet, and E is the 5^th letter. Subtracting 2 positions gives: G - 2 = E.
- Second letter: H is the 8^th letter of the alphabet, and F is the 6^th letter. Subtracting 2 positions gives: H - 2 = F.

2. Apply the exact same pattern to the third letter-pair, CD:
- First letter: C is the 3^rd letter of the alphabet. Subtracting 2 positions gives: C - 2 = A (1^st letter).
- Second letter: D is the 4^th letter of the alphabet. Subtracting 2 positions gives: D - 2 = B (2^nd letter).

Combining the resulting letters yields AB.