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: ( 18 ) 7 x ( 5832 ) - 2 ÷ ( 324 ) - 1 = ( 18 ) 7 
Options: a ) 5 , b ) 4 , c ) 3 , d ) 2 , e ) 1

Ex Output:
c


Ex Input:
Problem: the tax on a commodity is diminished by 40 % but its consumption is increased by 25 % . find the decrease percent in the revenue derived from it ? 
Options: a ) 18 % , b ) 72 % , c ) 25 % , d ) 12 % , e ) 52 %

Ex Output:
c


Ex Input:
Problem: compute all real solutions to 16 x + 4 x + 1 - 96 = 0 
Options: a ) 3 / 2 , b ) 3 / 3 , c ) 2 / 4 , d ) 4 / 4 , e ) 4 / 5

Ex Output:

a