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 motorcyclist started riding at highway marker a, drove 120 miles to highway marker b, and then, without pausing, continued to highway marker c, where she stopped. the average speed of the motorcyclist, over the course of the entire trip, was 45 miles per hour. if the ride from marker a to marker b lasted 3 times as many hours as the rest of the ride, and the distance from marker b to marker c was half of the distance from marker a to marker b, what was the average speed, in miles per hour, of the motorcyclist while driving from marker b to marker c ?
Options: a. 40, b. 45, c. 50, d. 55, e. 60
Output:
e