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: in a certain math department , students are required to enroll in either calculus or trigonometry , each of which is offered in beginner and advanced courses . the number of students enrolled in trigonometry is 50 % greater than the number of students enrolled in calculus , and 80 % of calculus students are enrolled in the beginner course . if 4 / 5 of students are in the beginner courses , and one student is selected at random , what is the probability that an advanced trigonometry student is selected ? 
Options: a ) 8 % , b ) 12 % , c ) 16 % , d ) 20 % , e ) 24 %
Example Output: b

Example Input: Problem: a money lender finds that due to a fall in the annual rate of interest from 8 % to 7 2 / 7 % his yearly income diminishes by rs . 61.50 . his capital is 
Options: a ) 22.378 , b ) 87.86 , c ) 246.0 , d ) 78.88 , e ) 127.71
Example Output: b

Example Input: Problem: a shopkeeper sells his goods at cost price but uses a faulty meter that weighs 990 grams . find the profit percent . 
Options: a ) 1.05 , b ) 1.06 , c ) 1.01 , d ) 1.08 , e ) 1.09
Example Output:
c