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: what is the area of a regular hexagon with sides 1 in. long ?
Options: a. 1.59 square inch, b. 2.59 square inch, c. 3.59 square inch, d. 4.59 square inch, e. 2.69 square inch
Example Output: b

Example Input: Problem: what is the smallest number by which 2880 must be divided in order to make it into a perfect square ?
Options: a. 3, b. 4, c. 5, d. 6, e. 7
Example Output: c

Example Input: Problem: a rectangle measures 8 cm on length and its diagonal measures 17 cm. what is the perimeter of the rectangle ?
Options: ['a. 44 cm', 'b. 42 cm', 'c. 46 cm', 'd. 49 cm', 'e. 41 cm']
Example Output:
c