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: if john makes a contribution to a charity fund at school, the average contribution size will increase by 50 % reaching $ 75 per person. if there were 1 other contributions made before john ' s, what is the size of his donation ?
Options: a. $ 100, b. $ 150, c. $ 200, d. $ 250, e. $ 450

Ex Output:
a


Ex Input:
Problem: p has $ 32 more than what q and r together would have had if both b and c had 1 / 6 of what p has. how much does p have ?
Options: a. $ 44, b. $ 48, c. $ 52, d. $ 56, e. $ 60

Ex Output:
b


Ex Input:
Problem: my grandson is about as many days as my son in weeks, and my grandson is as many months as i am in years. my grandson, my son and i together are 120 years. can you tell me my age in years ?
Options: a. 65, b. 72, c. 44, d. 73, e. 89

Ex Output:

b