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: a retailer bought a machine at a wholesale price of $ 90 and later on sold it after a 10 % discount of the retail price . if the retailer made a profit equivalent to 20 % of the whole price , what is the retail price t of the machine ? 
Options: a ) 81 , b ) 100 , c ) 120 , d ) 135 , e ) 160
Example Output: c

Example Input: Problem: an agent , gets a commission of 4 % on the sales of cloth . if on a certain day , he gets rs . 12.50 as commission , the cloth sold through him on that day is worth 
Options: a ) 312 , b ) 500 , c ) 887 , d ) 299 , e ) 132
Example Output: a

Example Input: Problem: a survey was sent to 95 customers , 7 of whom responded . then the survey was redesigned and sent to another 63 customers , 9 of whom responded . by approximately what percent did the response rate increase from the original survey to the redesigned survey ? 
Options: a ) 2 % , b ) 5 % , c ) 7 % , d ) 28 % , e ) 63 %
Example Output:
c