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: an escalator moves towards the top level at the rate of 7 ft . sec and its length is 180 feet . if a person walks on the moving escalator at the rate of 2 feet per second towards the top level , how much time does he take to cover the entire length . 
Options: a ) 5 sec , b ) 25 sec , c ) 20 sec , d ) 15 sec , e ) 10 sec
Example Output: c

Example Input: Problem: a , b and c enter into partnership . a invests some money at the beginning , b invests double the amount after 6 months , and c invests thrice the amount after 8 months . if the annual gain be rs . 21000 . a ' s share is ? 
Options: a ) 2999 , b ) 2778 , c ) 7000 , d ) 2889 , e ) 6612
Example Output: c

Example Input: Problem: by selling an article at rs . 600 , a profit of 60 % is made . find its cost price ? 
Options: a ) 228 , b ) 267 , c ) 375 , d ) 480 , e ) 811
Example Output:
c