Final answer:
The amber warning lights on a vehicle, such as a school bus, should be activated at least 200 feet before stops.
Step-by-step explanation:
The correct answer is 200 feet. The amber warning lights on a vehicle, such as a school bus, indicate that the vehicle is about to stop. These lights are activated a certain distance before the stop to alert other drivers to slow down and be prepared to stop. In this case, the amber warning lights should be activated at least 200 feet before stops.