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: the ration of the father ’ s age to his son ’ s age is 7 : 3 . the product of their ages is 756 . the ratio of their ages after 6 years will be : 
Options: a ) 5 : 2 , b ) 2 : 1 , c ) 11 : 7 , d ) 13 : 9 , e ) none of these

Output: b


Input: Consider Input: Problem: the average of first three prime numbers greater than 5 is ? 
Options: a ) 12.6 , b ) 12.9 , c ) 22.3 , d ) 10.3 , e ) 12.7

Output: d


Input: Consider Input: Problem: find the sum the difference between the compound and s . i . on a certain sum of money for 2 years at 10 % per annum is rs . 15 of money ? 
Options: a ) 1500 , b ) 2677 , c ) 1997 , d ) 2677 , e ) 1971


Output: a