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: of 30 applicants for a job, 9 had at least 4 years ' experience, 18 had degrees, and 3 had less than 4 years ' experience and did not have a degree. how many of the applicants had at least 4 years ' experience and a degree ?
Options: a. 14, b. 10, c. 9, d. 7, e. 5
Example Output: b

Example Input: Problem: a shopkeeper sells 500 metres of cloth for rs. 18000 at a loss of rs. 5 per metre. find his cost price for one metre of cloth ?
Options: a. 12, b. 27, c. 29, d. 50, e. 41
Example Output: e

Example Input: Problem: a tradesman by means of his false balance defrauds to the extent of 20 % ? in buying goods as well as by selling the goods. what percent does he gain on his outlay ? a. 20 % b. 45 %
Options: a. 77, b. 66, c. 44, d. 99, e. 11
Example Output:
c