What type of airspace is typically used for military operations?

Restricted airspace is specifically designated for military operations and is used to ensure the safety and security of both the airspace and any operations being conducted within it. This type of airspace is established to restrict access to unauthorized aircraft, which may pose a risk during military training exercises or operations. Air traffic control manages this airspace to prevent civilian aircraft from entering when it is active, thereby reducing the potential for conflicts or accidents.

In contrast, commercial airspace typically serves civil aviation operations and is not allocated for military purposes. Visual Flight Rules (VFR) airspace encompasses areas where pilots can operate under visual conditions without relying solely on instruments, but this can include both military and non-military flights. Class D airspace is associated with airports that have air traffic control towers and primarily pertains to the movement of civilian aircraft. Therefore, restricted airspace is the correct choice as it is the defined area for military activities.