Which components are key elements of the airspace system?

The correct answer highlights the distinction between controlled and uncontrolled airspace, which are fundamental components of the airspace system. Controlled airspace is designated airspace where air traffic control services are provided to regulate traffic and ensure safe separation between aircraft, often characterized by specific altitude limits and access requirements. This includes airspace classes like A, B, C, D, and E.

Uncontrolled airspace, on the other hand, does not have the same level of traffic management from air traffic control and is typically where pilots operate under visual flight rules (VFR). Understanding the difference between these types of airspace is critical for pilots as it impacts flight operations, navigation strategies, and communications with air traffic controllers.

The other options, while related to aviation, do not encompass the comprehensive and structured nature of the airspace system in the same way. Focusing solely on commercial airspace would ignore the vast swath of airspace that is used for non-commercial activities, while emergency landing zones and ground handling spaces pertain more to specific operational aspects rather than the overarching airspace structure.