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: if a sum of money doubles itself in 20 years at simple interest, the ratepercent per annum is
Options: a. 12, b. 12.5, c. 13, d. 5, e. 14

Output: d


Input: Consider Input: Problem: in n is a positive integer less than 200, and 14 n / 60 is an integer, then n has how many different positive prime factors s ?
Options: a. 2, b. 3, c. 5, d. 6, e. 8

Output: b


Input: Consider Input: Problem: on the first day of her vacation, louisa traveled 160 miles. on the second day, traveling at the same average speed, she traveled 280 miles. if the 160 - mile trip took 3 hours less than the 280 - mile trip, what was the average speed, in miles per hour ?
Options: a. 40, b. 45, c. 46, d. 48, e. 50


Output: a