Mr. Smith is designing a race where velocity will be measured. Which course would allow velocity to accurately get a winner?
A: A 5-mile course from the center of town heading north to the outskirts of town
B: A 100 mater swim in a 50-meter pool
C: A 2 mile run around a 400-meter track
D: A 10-mile bike course that zigzags through the mountains and back again