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'.

Ex Input:
Problem: how many liters of water must be evaporated from 50 liters of a 2 - percent sugar solution to get a 10 - percent solution ? 
Options: a ) 25 , b ) 30 , c ) 35 , d ) 40 , e ) 45

Ex Output:
d


Ex 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

Ex Output:
c


Ex Input:
Problem: a trader bought a car at 20 % discount on its original price . he sold it at a 100 % increase on the price he bought it . what percent of profit did he make on the original price ? 
Options: a ) 18 % , b ) 13 % , c ) 60 % , d ) 40 % , e ) 15 %

Ex Output:

c