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.

Ex Input:
Problem: the ratio of the volumes of two cubes is 1331: 2197. what is the ratio of their total surface areas ?
Options: a. 121: 169, b. 169: 122, c. 81: 124, d. 81: 126, e. 81: 129

Ex Output:
a

Ex Input:
Problem: at a certain university, 65 % of the professors are women, and 70 % of the professors are tenured. if 90 % of the professors are women, tenured, or both, then what percent of the men are tenured ?
Options: a. 25, b. 37.5, c. 50, d. 62.5, e. 75

Ex Output:
d

Ex Input:
Problem: fox jeans regularly sell for $ 15 a pair and pony jeans regularly sell for $ 18 a pair. during a sale these regular unit prices are discounted at different rates so that a total of $ 9 is saved by purchasing 5 pairs of jeans: 3 pairs of fox jeans and 2 pairs of pony jeans. if the sum of the two discounts rates is 25 percent, what is the discount rate on pony jeans ?
Options: a. 9 %, b. 10 %, c. 11 %, d. 12 %, e. 25 %

Ex Output:
e