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: set a contains all the even numbers between 2 and 50 inclusive. set b contains all the even numbers between 62 and 110 inclusive. what is the difference between the sum of elements of set b and the sum of the elements of set a ?
Options: a. 1500, b. 3100, c. 4400, d. 6200, e. 7400

Ex Output:
a


Ex Input:
Problem: a fort had provision of food for 150 men for 45 days. after 15 days, 10 men left the fort. the number of days for which the remaining food will last, is :
Options: a. 32, b. 37 1 / 4, c. 42, d. 54, e. 45

Ex Output:
a


Ex Input:
Problem: water is leaking out from a cylinder container at the rate of 0.31 m ^ 3 per minute. after 10 minutes, the water level decreases 16 meters. what is value of the radius in meters ?
Options: a. 1 / 2, b. 1 / 3, c. 1 / 4, d. 1 / 6, e. 1 / 8

Ex Output:

c