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: find large number from below question the difference of two numbers is 1000. on dividing the larger number by the smaller, we get 10 as quotient and the 10 as remainder
Options: a. 1234, b. 1110, c. 1456, d. 1200, e. 1600
Example Output: b

Example Input: Problem: cereal a is 10 % sugar by weight, whereas healthier but less delicious cereal b is 2 % sugar by weight. to make a delicious and healthy mixture that is 3 % sugar, what should be the ratio of cereal a to cereal b, by weight ?
Options: a. 2: 9, b. 2: 7, c. 1: 7, d. 1: 4, e. 1: 3
Example Output: c

Example Input: Problem: a 10000 liter tank, half - full of water is being filled from a pipe with a flow rate of 1 kiloliter every 2 minutes. at the same time, the tank is losing water from two drains at a rate of 1 kiloliter every 4 minutes and every 6 minutes. how many minutes does it take to fill the tank completely ?
Options: a. 8, b. 12, c. 18, d. 24, e. 60
Example Output:
e