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'.

Example Input: Problem: ( 112 x 5 ^ 4 ) = ? 
Options: a ) 70000 , b ) 80000 , c ) 90000 , d ) 90090 , e ) 100000
Example Output: a

Example Input: Problem: 5 drainage pipes , each draining water from a pool at the same constant rate , together can drain a certain pool in 16 days . how many additional pipes , each draining water at the same constant rate , will be needed to drain the pool in 4 days ? 
Options: a ) 6 , b ) 9 , c ) 10 , d ) 12 , e ) 15
Example Output: e

Example Input: Problem: is two years older than b who is twice as old as c . if the total of the ages of a , b and c be 42 , then how old is b ? 
Options: a ) 16 , b ) 8 , c ) 9 , d ) 10 , e ) 11
Example Output:
a