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: two boys starts from the same place walking at the rate of 5.5 kmph and 7.5 kmph respectively in the same direction . what time will they take to be 32 km apart ? 
Options: a ) 18 , b ) 16 , c ) 19 , d ) 15 , e ) 34
Example Output: b

Example Input: Problem: a shopkeeper sold 50 articles at the cost price of 60 articles . then find the profit % or lost % 
Options: a ) 20 % , b ) 22 % , c ) 25 % , d ) 30 % , e ) 35 %
Example Output: a

Example Input: Problem: what is the rate percent when the simple interest on rs . 1600 amount to rs . 200 in 4 years ? 
Options: a ) 4 % , b ) 3.125 % , c ) 5 % , d ) 6 % , e ) 7 %
Example Output:
b