How long does it take to stop under ideal conditions at 55 mph, according to the provided data?

Answer: B — 4 to 4.5 seconds

When driving at a speed of 55 mph, various factors come into play when determining the stopping distance and time. Under ideal conditions, such as good weather and a well-maintained vehicle, the average perception-reaction time and the physical stopping time must be considered together. Typically, it takes about 1.5 seconds for a driver to perceive a hazard and react before actually applying the brakes. Once the brakes are applied, the vehicle continues to move forward for a distance until it comes to a complete stop. At 55 mph, the braking distance alone takes approximately 2.5 to 3 seconds depending on various factors such as road conditions and vehicle weight. Thus, when combining both the perception-reaction time and the braking time, the total time to stop would indeed be around 4 to 4.5 seconds. This duration accounts for both the time taken to recognize the need to stop and the time taken to bring the vehicle to a complete halt, making this choice the most realistic to the scenario described.