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'.

Ex Input:
Problem: some of 50 % - intensity red paint is replaced with 20 % solution of red paint such that the new paint intensity is 40 % . what fraction of the original paint was replaced ? 
Options: a ) 1 / 3 , b ) 1 / 5 , c ) 2 / 3 , d ) 3 / 4 , e ) 4 / 5

Ex Output:
a


Ex Input:
Problem: an error 10 % in excess is made while measuring the side of a square . now what is the percentage of error in the calculated area of the square ? 
Options: a ) 6.64 % , b ) 16.64 % , c ) 15.64 % , d ) 21 % , e ) 10.64 %

Ex Output:
d


Ex Input:
Problem: the cost price of an article is 64 % of the marked price . calculate the gain percent after allowing a discount of 25 % ? 
Options: a ) 37.5 % , b ) 37.6 % , c ) 38.5 % , d ) 17.1 % , e ) 37.2 %

Ex Output:

d