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: on a certain transatlantic crossing , 40 percent of a ship ’ s passengers held round - trip tickets and also took their cars abroad the ship . if 20 percent of the passengers with round - trip tickets did not take their cars abroad the ship , what percent of the ship ’ s passengers held round - trip tickets ? 
Options: a ) 20 % , b ) 40 % , c ) 50 % , d ) 60 % , e ) 80 %
Example Output: c

Example Input: Problem: if a lends rs . 2000 to b at 15 % per annum and b lends the same sum to c at 17 % per annum then the gain of b in a period of 4 years is ? 
Options: a ) 155 , b ) 162 , c ) 157.5 , d ) 160 , e ) 157.12
Example Output: d

Example Input: Problem: during a sale , the price of a pair of shoes is marked down 15 % from the regular price . after the sale ends , the price goes back to the original price . what is the percent of increase to the nearest percent from the sale price back to the regular price for the shoes ? 
Options: a ) 9 % , b ) 10 % , c ) 11 % , d ) 18 % , e ) 90 %
Example Output:
d