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: a bag contains 12 red marbles. if someone were to remove 2 marbles from the bag, one at a time, and replace the first marble after it was removed, the probability that neither marble would be red is 25 / 36. how many marbles are in the bag ?
Options: a. 24, b. 48, c. 60, d. 72, e. 84

Ex Output:
b


Ex Input:
Problem: the smallest number which when diminished by 2, is divisible by 12, 16, 18, 21 and 28 is
Options: a. 1008, b. 1010, c. 1022, d. 1032, e. 1043

Ex Output:
b


Ex Input:
Problem: the compound ratio of 2 / 3, 6 / 7, 4 / 3 and 1 / 8 is given by ?
Options: a. 2 / 21, b. 1 / 48, c. 1 / 98, d. 1 / 96, e. 1 / 68

Ex Output:

a