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: a man can row his boat with the stream at 19 km / h and against the stream in 11 km / h . the man ' s rate is ? 
Options: a ) 4 kmph , b ) 2 kmph , c ) 7 kmph , d ) 8 kmph , e ) 3 kmph
Example Output: a

Example Input: Problem: in how many years rs 160 will produce the same interest at 8 % as rs . 500 produce in 4 years at 8 % 
Options: a ) 13 , b ) 13.5 , c ) 11.5 , d ) 12.5 , e ) 12
Example Output: d

Example Input: Problem: a shopkeeper has 280 kg of apples . he sells 50 % of these at 20 % profit and remaining 60 % at 30 % profit . find his % profit on total . 
Options: a ) 24 % , b ) 25 % , c ) 26 % , d ) 28 % , e ) 35 %
Example Output:
d