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: what will be the difference between simple and compound interest @ 20 % per annum on a sum of $ 500 after 2 years ? 
Options: a ) $ 10 , b ) $ 20 , c ) $ 25 , d ) $ 30 , e ) $ 40
Example Output: b

Example Input: Problem: a present value of a machine is $ 900 . its value depletiation rate is 25 % per annum then find the machine value before 2 years ? 
Options: a ) $ 1500 , b ) $ 1200 , c ) $ 1600 , d ) $ 1000 , e ) $ 1350
Example Output: c

Example Input: Problem: a bowl was filled with 10 ounces of water , and 0.004 ounce of the water evaporated each day during a 50 - day period . what percent of the original amount of water evaporated during this period ? 
Options: a ) 0.004 % , b ) 0.04 % , c ) 0.40 % , d ) 2 % , e ) 40 %
Example Output:
d