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: a reduction of 20 % in the price of salt enables a lady to obtain 10 kgs more for rs . 400 , find the original price per kg ? 
Options: a ) s . 7 , b ) s . 9 , c ) s . 10 , d ) s . 11 , e ) s . 19
Example Output: c

Example Input: Problem: a sum of $ 1000 amounts to $ 1500 in 5 years at simple interest . if the interest rate is increased by 5 % it would amount to how much ? 
Options: a ) $ 1000 , b ) $ 750 , c ) $ 1541 , d ) $ 1478 , e ) $ 1750
Example Output: e

Example Input: Problem: 37 . if the cost price of 15 tables be equal to the selling price of 20 tables , the loss per cent is ? 
Options: a ) 20 % , b ) 30 % , c ) 25 % , d ) 37.5 % , e ) 38 %
Example Output:
c