The correct answer is A. 500 vehicles per hour.
A rotary is a type of intersection where traffic flows in a circular pattern. It is designed to improve traffic flow by allowing vehicles to enter and exit the intersection without having to stop. However, rotaries can become congested if too many vehicles are trying to use them.
The maximum number of vehicles that can safely use a rotary is typically limited by the number of lanes in the rotary and the speed at which vehicles can travel through it. In general, a rotary can handle up to 500 vehicles per hour. If more than 500 vehicles are trying to use the rotary, it can become congested and traffic can back up.
Option B is incorrect because 500 vehicles per day is a much lower number than the maximum number of vehicles that can safely use a rotary. Option C is incorrect because 5000 vehicles per hour is much higher than the maximum number of vehicles that can safely use a rotary. Option D is incorrect because 5000 vehicles per day is a much lower number than the maximum number of vehicles that can safely use a rotary.