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 smallest number which, when increased by 7, is divisible by 8, 11, and 24 ?
Options: a. 264, b. 257, c. 269, d. 270, e. 282
Example Output: b

Example Input: Problem: a van takes 5 hours to cover a distance of 495 km. what speed in kph should the van maintain to cover the same distance in 3 / 2 of the previous time ?
Options: a. 60, b. 63, c. 66, d. 69, e. 72
Example Output: c

Example Input: Problem: if there are 86 workers in a factory, and on a certain day, 72 were present. calculate the percentage that showed up for work ? ( round to the nearest tenth ).
Options: a. 82.7 %, b. 81.7 %, c. 83.7 %, d. 89.7 %, e. 88.7 %
Example Output:
c