Which of the following best describes the outer ring of Class C airspace in terms of radius?

In the context of Class C airspace, the outer ring is indeed defined by a radius of 10 nautical miles from the airport reference point. This designation serves an important function, as it establishes a boundary within which specific air traffic control procedures are applied to separate and manage aircraft traffic effectively.

The Class C airspace system is structured with an inner core that usually has a radius of 5 nautical miles, extending from the surface up to 4,000 feet, and the outer ring, which generally extends from the outer boundary of the inner circle to the ceiling of the Class C airspace, up to 10 nautical miles. This layered approach allows for better organization of air traffic and enhances safety in regions where airport traffic, including general aviation and commercial flights, can be considerable.

Understanding these dimensions is crucial for pilots operating within Class C airspace to ensure compliance with regulations and to facilitate smooth communication with air traffic control.