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: bruce and anne can clean their house in 4 hours working together at their respective constant rates. if anne ’ s speed were doubled, they could clean their house in 3 hours working at their respective rates. how many w hours does it currently take anne to clean the house on her own ?
Options: a. 6, b. 7, c. 8, d. 12, e. 14

Output: d


Input: Consider Input: Problem: two trains travel in opposite directions at 36 kmph and 45 kmph and a man sitting in slower train passes the faster train in 8 seconds. the length of the faster train is
Options: a. 80 m, b. 100 m, c. 120 m, d. 180 m, e. 160 m

Output: b


Input: Consider Input: Problem: convert 0.36 in to a vulgar fraction ?
Options: a. 18 / 50, b. 16 / 50, c. 17 / 50, d. 9 / 25, e. none


Output: d