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: an error 6 % in excess is made while measuring the side of a square . the percentage of error in the calculated area of the square is : 
Options: a ) 12.36 , b ) 8.36 , c ) 9.36 , d ) 10.36 , e ) 11.36
Example Output: a

Example Input: Problem: 33 1 / 3 % of 360 ? 
Options: a ) 80 , b ) 90 , c ) 110 , d ) 120 , e ) 130
Example Output: d

Example Input: Problem: 10 % of ( 50 % of $ 500 ) is ? 
Options: a ) $ 15 , b ) $ 20 , c ) $ 25 , d ) $ 30 , e ) $ 22
Example Output:
c