What characteristic describes Class B airspace?

Class B airspace is specifically designed to manage high-density traffic around major airports to ensure safe and efficient operations. It typically surrounds the busiest airports in a series of layers that extend vertically from the surface to a specified altitude, forming a controlled airspace where air traffic control services are provided. This configuration allows for the safe separation of aircraft, considering the increased volume of operations in these areas.

The other characteristics of Class B airspace are not accurate. For instance, it does not cover uncontrolled airspace (which is typically found at lower altitudes under Class G), it is not limited to zero altitude over city centers, and it is not restricted only to remote areas. The primary function of Class B airspace is to manage traffic flow in and out of major airports, making its layered structure around these locations essential for preventing collisions and ensuring all aircraft operate safely within that space.