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 gambler has won 40 % of his 30 poker games for the week so far . if , all of a sudden , his luck changes and he begins winning 80 % of the time , how many more games must he play to end up winning 60 % of all his games for the week ? 
Options: a ) 20 , b ) 25 , c ) 30 , d ) 35 , e ) 40
Example Output: c

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: a money lender lent rs . 800 at 3 % per year and rs . 1400 at 5 % per year . the amount should be returned to him when the total interest comes to rs . 350 . find the number of years . 
Options: a ) 3.5 , b ) 3.72 , c ) 4 , d ) 4.25 , e ) 4.5
Example Output:
b