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 the population of a certain country increases at the rate of one person every 15 seconds, by how many persons does the population increase in 25 minutes ?
Options: a. 80, b. 100, c. 150, d. 240, e. 300

Output: b


Input: Consider Input: Problem: a person crosses a 800 m long street in 5 minutes. what is his speed in km per hour ?
Options: a. 1.23, b. 2.86, c. 4.36, d. 9.25, e. 9.61

Output: e


Input: Consider Input: Problem: if a tire rotates at 400 revolutions per minute when the car is traveling 48 km / h, what is the circumference of the tire ?
Options: a. 7 meters, b. 9 meters, c. 8 meters, d. 2 meters, e. 3 meters


Output: d