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: the tax on a commodity is diminished by 30 % but its consumption is increased by 15 % . find the decrease percent in the revenue derived from it ? 
Options: a ) 20 % , b ) 18 % , c ) 15 % , d ) 12 % , e ) 14 %
Example Output: a

Example Input: Problem: find the value of ( 55 + 113 / 78 ) × 78 
Options: a ) 4423 , b ) 4403 , c ) 4413 , d ) 2403 , e ) 4375
Example Output: b

Example Input: Problem: 3251 + 587 + 369 - ? = 3007 
Options: a ) 1250 , b ) 1300 , c ) 1375 , d ) 1200 , e ) none of them
Example Output:
d