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 number must be added to 6, 16 and 8 to get an average of 13 ?
Options: a. 23, b. 22, c. 44, d. 33, e. 55

Ex Output:
b


Ex Input:
Problem: how much more would rs. 10000 fetch, after two years, if it is put at 20 % p. a. compound interest payable half yearly than if is put at 20 % p. a. compound interest payable yearly ?
Options: a. 241, b. 725, c. 992, d. 837, e. 923

Ex Output:
a


Ex Input:
Problem: which number can we add to 425897 to get a number exactly divisible by 456 ?
Options: a. 3, b. 5, c. 7, d. 9, e. 11

Ex Output:

c