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: if the price of gasoline increases by 25 % and a driver intends to spend only 5 % more on gasoline , by how much percent should the driver reduce the quantity of gasoline that he buys ?
Options: a ) 20 % , b ) 16 % , c ) 15 % , d ) 12 % , e ) 10 %

Ex Output:
b

Ex Input:
Problem: what is the minimum percentage increase in the mean of set f { - 4 , - 1 , 0 , 6 , 9 } if its two smallest elements are replaced with two different primes ?
Options: a ) 25 % , b ) 50 % , c ) 75 % , d ) 100 % , e ) 200 %

Ex Output:
d

Ex Input:
Problem: a salesman ' s terms were changed from a flat commission of 5 % on all his sales to a fixed salary of rs . 900 plus 2.5 % commission on all sales exceeding rs . 4,000 . if his remuneration as per new scheme was rs . 600 more than that by the previous schema , his sales were worth ?
Options: a ) 10000 , b ) 12000 , c ) 12019 , d ) 12197 , e ) 12012

Ex Output:
a