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'.

Ex 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

Ex Output:
b


Ex Input:
Problem: 48.95 - 32.006 = ? 
Options: a ) 16.089 , b ) 16.35 , c ) 16.89 , d ) 16.944 , e ) none of them

Ex Output:
d


Ex Input:
Problem: what least number should be added to 1056 , so that the sum is completely divisible by 23 
Options: a ) 4 , b ) 1 , c ) 2 , d ) 3 , e ) 5

Ex Output:

c