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: the average of first 10 natural numbers is ?
Options: a. 5.6, b. 5.5, c. 5.1, d. 5.8, e. 5.2
Example Output: b

Example Input: Problem: what is the rate percent when the simple interest on rs. 1600 amount to rs. 200 in 4 years ?
Options: a. 4 %, b. 3.125 %, c. 5 %, d. 6 %, e. 7 %
Example Output:
b