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: joe invested a certain sum of money in a simple interest bond whose value grew to $ 310 at the end of 3 years and to $ 410 at the end of another 5 years . what was the rate of interest in which he invested his sum ? 
Options: a ) 6 % , b ) 7 % , c ) 8 % , d ) 9 % , e ) 10 %
Example Output: c

Example Input: Problem: how many liters of water must be evaporated from 50 liters of a 8 - percent sugar solution to get a 10 - percent solution ? 
Options: a ) 8 , b ) 10 , c ) 12 , d ) 14 , e ) 16
Example Output: b

Example Input: Problem: a shop owner sells 25 mtr of cloth and gains sp of 10 mtrs . find the gain % ? 
Options: a ) 30 % , b ) 40 % , c ) 50 % , d ) 66.67 % , e ) 70 %
Example Output:
d