The correct answer is A. circular.
A circular rotary is the most common type of rotary. It is simple to design and construct, and it provides good visibility for drivers. Circular rotaries are also relatively efficient in terms of traffic flow.
A tangent rotary is a type of rotary in which the roads meet at a point. This type of rotary is less common than a circular rotary, but it can be used when there is limited space available. Tangent rotaries can be difficult to navigate, especially for drivers who are not familiar with them.
An elliptical rotary is a type of rotary in which the roads meet at two points. This type of rotary is even less common than a tangent rotary, but it can be used when there is very limited space available. Elliptical rotaries can be very difficult to navigate, and they are not recommended for use in high-traffic areas.
A turbine rotary is a type of rotary in which the roads meet at a central point. This type of rotary is very rare, and it is not recommended for use in most situations. Turbine rotaries can be very difficult to navigate, and they can be dangerous for drivers.
In conclusion, the correct answer is A. circular. A circular rotary is the most common type of rotary, and it is the best choice when only one of the roads is important.