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: the cost price of an article is 70 % of the marked price . calculate the gain percent after allowing a discount of 10 % . 
Options: a ) 13.6 % , b ) 28.6 % , c ) 35.6 % , d ) 42.3 % , e ) none
Example Output: b

Example Input: Problem: an article is bought for rs . 765 and sold for rs . 1000 , find the gain percent ? 
Options: a ) 30.6 % , b ) 30.5 % , c ) 30.7 % , d ) 30.8 % , e ) 30.9 %
Example Output:
c