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: 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
Example Output: b

Example Input: Problem: in a group of 100 people, 90 have an age of more 30 years, and the others have an age of less than 20 years. if a person is selected at random from this group, what is the probability the person ' s age is less than 20 ?
Options: a. 0.1, b. 0.55, c. 0.65, d. 0.75, e. 0.85
Example Output: a

Example Input: Problem: jack, jill, and sandy each have one try to make a basket from half court. if their individual probabilities of making the basket are 1 / 6, 1 / 7, and 1 / 8 respectively, what is the probability that jill and sandy will make a basket but jack will miss ?
Options: a. 3 / 168, b. 5 / 168, c. 7 / 168, d. 5 / 336, e. 7 / 336
Example Output:
d