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: what is the total number of integers between 10 and 50 that are divisible by 2 ?
Options: a. 18, b. 19, c. 22, d. 25, e. 10

Ex Output:
b


Ex Input:
Problem: two pipes a and b can fill a tank in 36 hours and 46 hours respectively. if both the pipes are opened simultaneously, how much time will be taken to fill the tank ?
Options: a. 20.195 hrs, b. 21.195 hrs, c. 22.195 hrs, d. 23.195 hrs, e. 20.495 hrs

Ex Output:
a


Ex Input:
Problem: the ratio between the length and the breadth of a rectangular plot is 7: 5. if the perimeter of the plot is 288 metres, what is its area ?
Options: ['a. 1320 sq. metres', 'b. 3260 sq. metres', 'c. 4280 sq. metres', 'd. 5040 sq. metres', 'e. none of these']

Ex Output:

d