In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: shop offered 20 % offer for every shirt , smith bought a shirt at rs . 780 . and what was the shop ' s original selling price ? 
Options: a ) 500 , b ) 550 , c ) 600 , d ) 700 , e ) 975
Example Output: e

Example Input: Problem: an agent , gets a commission of 2.5 % on the sales of cloth . if on a certain day , he gets rs . 21 as commission , the cloth sold through him on that day is worth 
Options: a ) 333 , b ) 500 , c ) 840 , d ) 299 , e ) 132
Example Output: c

Example Input: Problem: at what rate percent per annum will a sum of money double in 7 years . 
Options: a ) 12.5 % , b ) 13.5 % , c ) 14.2 % , d ) 14.5 % , e ) 21.5 %
Example Output:
c