Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Example Input: Problem: the denominator of a fraction is 7 greater than the numerator. if the numerator and the denominator are increased by 4, the resulting fraction is equal to 5 " 6. what is the value of the original fraction ?
Options: a. 23 / 30, b. 25 / 32, c. 31 / 38, d. 37 / 44, e. 47 / 54
Example Output: c

Example Input: Problem: a merchant marks goods up by 80 % and then offers a discount on the marked price. the profit that the merchant makes after offering the discount is 35 %. what % discount did the merchant offer ?
Options: a. 20 %, b. 25 %, c. 30 %, d. 35 %, e. 40 %
Example Output: b

Example Input: Problem: the average salary of all the workers in a workshop is rs. 8000. the average salary of 7 technicians is rs. 11000 and the average salary of the rest is rs. 6000. the total number of workers in the workshop is
Options: a. 14, b. 21, c. 22, d. 23, e. none
Example Output:
a