What is the maximum horizontal distance associated with the top of Class C airspace?

The correct answer indicates that Class C airspace extends horizontally a maximum of 10 nautical miles from the center of the airport. Class C airspace is typically designated around airports that have a significant amount of air traffic and require specific communication and operational protocols from pilots who operate within that space.

The boundaries of Class C airspace are designed to provide both separation and safety for aircraft operating in and around busy airports. Beyond the 10 NM limit, there are usually additional airspace classes where different rules apply, such as Class D or Class E, depending on the proximity to the airport. Understanding the dimensions of Class C airspace is crucial for pilots and air traffic controllers because it helps manage the flow of air traffic and ensures safety in areas where more frequent aircraft operations occur.

In context, the other options related to horizontal distances beyond 10 nautical miles don't correspond with the established dimensions of Class C airspace, making those distances inaccurate.