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: what is the normal price of an article sold at $ 72 after two successive discounts of 10 % and 20 % ?
Options: a. $ 92, b. $ 96, c. $ 100, d. $ 104, e. $ 108
Example Output: c

Example Input: Problem: 54671 - 14456 - 31466 = ?
Options: a. 2449, b. 5449, c. 8749, d. 8449, e. 6468
Example Output: c

Example Input: Problem: the average age of 8 men increases by 2 years when two women are included in place of two men of ages 20 and 22 years. find the average age of the women ?
Options: a. 87, b. 98, c. 30, d. 29, e. 37
Example Output:
d