A car is traveling with a constant speed of 20.0 m/s when the driver suddenly applies the brakes, causing the car to slow down with a constant acceleration. The car comes to a stop in a distance of 50 m. What was the magnitude of acceleration of the car as it slowed down? A) 3.75 m/s^2 B) 4.00 m/s^2 C) 4.25 m/s^2 D) 4.50 m/s^2 E) 4.75 m/s^2