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: the speed of the boat in still water in 12 kmph. it can travel downstream through 48 kms in 3 hrs. in what time would it cover the same distance upstream ?
Options: a. 8 hours, b. 6 hours, c. 4 hours, d. 5 hours, e. 6 hours

Output: e


Input: Consider Input: Problem: if jack walked 8 miles in 1 hour and 15 minutes, what was his rate of walking in miles per hour ?
Options: a. 4, b. 4.5, c. 6, d. 6.4, e. 15

Output: d


Input: Consider Input: Problem: if a: b = 3: 4, b: c = 7: 9, c: d = 5: 7, find a: d ?
Options: a. 5 / 12, b. 5 / 15, c. 5 / 10, d. 5 / 11, e. 5 / 13


Output: a


