Analyze the relationship between the letters of each pair:
- (1) NTP → PGR
Check positions:
N → P (+2), T → G (-13), P → R (+2)
- (2) RSB → THD
R → T (+2), S → H (-11), B → D (+2)
- (3) KGN → MTP
K → M (+2), G → T (+13), N → P (+2)
- (4) QDL → SWP
Q → S (+2), D → W (-7), L → P (+4)
Clearly, the first three options follow a pattern where the 1st and 3rd letters increase by +2, but the middle letter shows a large jump that doesn’t fit a simple rule. However, in option (4), the third letter increases by +4, breaking the pattern.
So, Option (4) QDL : SWP is the odd one out.