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.

Input: Consider Input: Problem: ages of two persons differ by 20 years. if 6 year ago, the elder one be 3 times as old the younger one, find their present age
Options: a. 12,28, b. 14,30, c. 16,36, d. 18,34, e. 19,34

Output: c


Input: Consider Input: Problem: the total age of a and b is 16 years more than the total age of b and c. c is how many year younger than
Options: a. 14 years, b. 12 years, c. 56 years, d. 16 years, e. 55 years

Output: d


Input: Consider Input: Problem: john has 10 pairs of matched socks. if he loses 3 individual socks, what is the greatest number of pairs of matched socks he can have left ?
Options: a. 7, b. 8, c. 5, d. 4, e. 3


Output: b