In the following question, four letter pairs are given. The letters on left side of (–) is related to the letters on the right side of (–) with some Logic/Rule/Relation. Three are similar on basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives.

Correct option is C

Analyzing Each Option:
1. BA – HG
· B to H: Move forward by 6 letters in the alphabet.
· A to G: Move forward by 6 letters.
2. SQ – YW
· S to Y: Move forward by 6 letters.
· Q to W: Move forward by 6 letters.
3. MD – SK
· M to S: Move forward by 6 letters.
· D to K: Move forward by 7 letters.
4. JY – PE
· J to P: Move forward by 6 letters.
· Y to E: Move forward by 6 letters (wrapping around the alphabet).
Conclusion:
In options (a), (b), and (d), both letters move forward by exactly 6 positions in the alphabet. However, in option (c), the first letter moves forward by 6 positions, but the second letter moves forward by 7 positions.
Answer:
The correct answer is: MD – SK