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: during a thanksgiving weekend , a car rental company rented 6 - tenths of their vehicles , including two - fifths of the 4 wds that it had . if 40 % of the vehicles are 4 wds , then what percent of the vehicles that were not rented were not 4 wds ? 
Options: a ) 20 % , b ) 30 % , c ) 40 % , d ) 50 % , e ) 60 %
Example Output: c

Example Input: Problem: a cycle is bought for rs . 900 and sold for rs . 1150 , find the gain percent ? 
Options: a ) 15 , b ) 20 , c ) 27.77 , d ) 40 , e ) 12
Example Output: c

Example Input: Problem: the sum of money will be double itself in 20 years and simple interest find rate of interest ? 
Options: a ) 10 % , b ) 5 % , c ) 15 % , d ) 20 % , e ) 25 %
Example Output:
b