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: if the cost price of 50 articles is equal to the selling price of 20 articles , then the gain or loss percent is ? 
Options: a ) 16 , b ) 127 , c ) 12 , d ) 18 , e ) 150
Example Output: e

Example Input: Problem: the difference between the compound interest compounded annually and simple interest for 2 years at 20 % per annum is rs . 72 . find the principal ? 
Options: a ) 2277 , b ) 2667 , c ) 3600 , d ) 2766 , e ) 1800
Example Output: e

Example Input: Problem: a reduction of 20 % in the price of oil enables a house wife to obtain 4 kgs more for rs . 600 , what is the reduced price for kg ? 
Options: a ) 20 , b ) 40 , c ) 36 , d ) 30 , e ) 35
Example Output:
d