Correct option is D
Given - 13:31::15:33::20:?
Logic = Second number = First number + 18
The relationship follows the logic of adding 18 to the given number.
In the first pair, 13 becomes 31 because 13+18=31.
In the second pair, 15 becomes 33 because 15+18=33.
In the third pair, 20 will become 38 because 20+18=38.
The correct answer is (D) 38.