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: joe invested a certain sum of money in a simple interest bond whose value grew to $ 310 at the end of 3 years and to $ 410 at the end of another 5 years . what was the rate of interest in which he invested his sum ? 
Options: a ) 6 % , b ) 7 % , c ) 8 % , d ) 9 % , e ) 10 %
Example Output: c

Example Input: Problem: a man can row his boat with the stream at 6 km / h and against the stream in 3 km / h . the man ' s rate is ? 
Options: a ) 1.5 kmph , b ) 3 kmph , c ) 8 kmph , d ) 7 kmph , e ) 5 kmph
Example Output: a

Example Input: Problem: a retailer purchases shirts from a wholesaler and then sells the shirts in her store at a retail price that is 80 percent greater than the wholesale price . if the retailer decreases the retail price by 20 percent this will have the same effect as increasing the wholesale price by what percent ? 
Options: a ) 26 , b ) 37.5 , c ) 42 , d ) 44 , e ) 50
Example Output:
d