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: out of 40 applicants to a law school, 15 majored in political science, 20 had a grade point average higher than 3.0, and 10 did not major in political science and had a gpa equal to or lower than 3.0. how many e applicants majored in political science and had a gpa higher than 3.0 ?
Options: a. 5, b. 10, c. 15, d. 25, e. 35
Example Output: a

Example Input: Problem: a group of hikers is planning a trip that will take them up a mountain using one route and back down using another route. they plan to travel down the mountain at a rate of one and a half times the rate they will use on the way up, but the time each route will take is the same. if they will go up the mountain at a rate of 7 miles per day and it will take them two days, how many miles long is the route down the mountain ?
Options: a. 18, b. 19, c. 20, d. 21, e. 22
Example Output: d

Example Input: Problem: if 20 men can build a water fountain 56 metres long in 14 days, what length of a similar water fountain can be built by 35 men in 3 days ?
Options: a. 21 m, b. 24 m, c. 27 m, d. 29 m, e. 30 m
Example Output:
a