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: in a room filled with 6 people, all 6 people have exactly 1 sibling in the room. if two individuals are selected from the room at random, what is the probability that those two individuals are not siblings ?
Options: a. 3 / 5, b. 4 / 5, c. 5 / 6, d. 5 / 12, e. 7 / 12

Ex Output:
b


Ex Input:
Problem: in a factory, an average of 60 tv ' s are produced per day for the fist 25 days of the months. a few workers fell ill for the next 5 days reducing the daily avg for the month to 58 sets / day. the average production per day for day last 5 days is ?
Options: a. 20, b. 36, c. 48, d. 50, e. 59

Ex Output:
c


Ex Input:
Problem: if a, b and c together can finish a piece of work in 4 days. a alone in 12 days and b in 18 days, then c alone can do it in ?
Options: a. 7 days, b. 3 days, c. 9 days, d. 8 days, e. 2 days

Ex Output:

c