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 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

Example Input: Problem: a store sells chairs and tables. if the price of 2 chairs and 1 table is 60 % of the price of 1 chair and 2 tables, and the price of 1 table and 1 chair is $ 64, what is the price, in dollars, of 1 table ? ( assume that every chair has the same price and every table has the same price. )
Options: a. 48, b. 52, c. 54, d. 58, e. 56
Example Output: e

Example Input: Problem: bruce and anne can clean their house in 4 hours working together at their respective constant rates. if anne ’ s speed were doubled, they could clean their house in 3 hours working at their respective rates. how many d hours does it currently take anne to clean the house on her own ?
Options: a. 6, b. 7, c. 8, d. 12, e. 14
Example Output:
d