Q: 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.
Problem: working simultaneously and independently at an identical constant rate, 5 machines of a certain type can produce a total of x units of product p in 4 days. how many of these machines, working simultaneously and independently at this constant rate, can produce a total of 2 x units of product p in 2 days ?
Options: a. 11, b. 13, c. 15, d. 18, e. 20
A:
e