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 particular library has 75 books in a special collection , all of which were in the library at the beginning of the month . these book are occasionally loaned out through an inter - library program . if , by the end of the month , 60 percent of books that were loaned out are returned and there are 65 books in the special collection at that time , how many books of the special collection were loaned out during that month ? 
Options: a ) 20 , b ) 25 , c ) 35 , d ) 40 , e ) 55
Example Output: b

Example Input: Problem: a trader mixes 80 kg of tea at 15 per kg with 20 kg of tea at cost price of 20 per kg . in order to earn a profit of 50 % , what should be the sale price of the mixed tea ? 
Options: a ) 23.75 , b ) 22 , c ) 20 , d ) 19.2 , e ) none of these
Example Output: e

Example Input: Problem: what is the rate percent when the simple interest on rs . 2000 amount to rs . 500 in 2 years ? 
Options: a ) 5 % , b ) 6 % , c ) 12.5 % , d ) 95 % , e ) 1 %
Example Output:
c