Correct option is D
The pattern here relates each pair of numbers by taking the sum of the digits of the first number:
For 32 : 5, the sum of the digits of 32 is 3+2=53 + 2 = 53+2=5.
For 76 : 13, the sum of the digits of 76 is 7+6=137 + 6 = 137+6=13.
Following the same pattern for 99 : ?:
The sum of the digits of 99 is 9+9=189 + 9 = 189+9=18.
Therefore, the number related to 99 is 18.