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: if each year the population of the country grows by 40 % , how many years will elapse before the population of the country doubles ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7
Example Output: a

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: one night a certain hotel rented 3 / 4 of its rooms . including 2 / 3 of their air conditioned rooms . if 3 / 5 of its rooms were air conditioned , what percent of the rooms that were not rented were air conditioned ? 
Options: a ) 20 , b ) 33 1 / 3 , c ) 35 , d ) 40 , e ) 80
Example Output:
e