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: kathleen can paint a room in 4 hours, and anthony can paint an identical room in 5 hours. how many hours would it take kathleen and anthony to paint both rooms if they work together at their respective rates ?
Options: a. 8 / 15, b. 40 / 9, c. 15 / 8, d. 9 / 4, e. 15 / 4

Ex Output:
b

Ex Input:
Problem: a no. when divided by 281 gives a remainder 160, what remainder will be obtainedby dividingthe same no. 21 ?
Options: a. 21, b. 22, c. 23, d. 24, e. 25

Ex Output:
a

Ex Input:
Problem: a can finish a work in 20 days, b in 15 days and c in 12 days. b and c start the work but are forced to leave after 2 days. the remaining work was done by a in :
Options: a. 10, b. 11, c. 12, d. 13, e. 14

Ex Output:
e