In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Input: Consider Input: Problem: a man is 20 years older than his son . in two years , his age will be twice the age of his son . the present age of the son is ?
Options: a ) 11 , b ) 25 , c ) 27 , d ) 18 , e ) 91

Output: d

Input: Consider Input: Problem: find the smallest number which leaves 2235 , 48 and 61 as remainders when divided by 26 , 39 , 52 and 65 respectively .
Options: a ) 67 , b ) 26 , c ) 99 , d ) 26 , e ) 91

Output: d

Input: Consider Input: Problem: 8597 - ? = 7429 - 4358
Options: a ) 3567 , b ) 6424 , c ) 6835 , d ) 5526 , e ) none of these
Output: d