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: the annual interest rate earned by an investment increased by 11 percent from last year to this year . if the annual interest rate earned by the investment this year was 22 percent , what was the annual interest rate last year ?
Options: a ) 17 % , b ) 19 % , c ) 18 % , d ) 20 % , e ) 22 %
Example Output: d

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 sum of money at simple interest amounts to rs . 815 in 3 years and to rs . 854 in 4 years . the sum is ?
Options: a ) 287 , b ) 278 , c ) 698 , d ) 279 , e ) 275
Example Output:
c