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: 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: 1 , 6 , 16 , 31 , 51 , ( . . . . ) 
Options: a ) 61 , b ) 66 , c ) 76 , d ) 86 , e ) 83
Example Output: b

Example Input: Problem: find the value of m 62519 x 9999 = m ? 
Options: a ) 724533811 , b ) 625127481 , c ) 545463251 , d ) 725117481 , e ) 677899932
Example Output:
b