Definition: 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: Problem: a can do a work in 6 days. b can do the same work in 12 days. if both a & b are working together in how many days they will finish the work ?
Options: a. 3, b. 5, c. 4, d. 2, e. 6
Output:
c