Airspace of defined dimensions, confined activities, and limitations imposed on non-users is identified as?

Special Use Airspace refers to airspace designated for specific purposes, where certain activities may be confined to designated areas, and limitations are imposed to protect non-users. This classification includes a variety of airspace that has restrictions based on specific activities such as military operations, flight training, or other governmental uses.

In contrast to controlled airspace, which is primarily about the management of aircraft operations and requires adherence to specific regulations to ensure safety, Special Use Airspace distinctly defines areas where specific activities occur, and control measures are necessary to mitigate risks to other users of the airspace.

Prohibited Airspace marks areas where flight is not allowed for security and safety reasons, while Restricted Airspace allows for controlled access but typically includes some restrictions and is used for activities that may be hazardous to non-participating aircraft. Thus, the definition of Special Use Airspace captures the essence of areas that are not just restricted but designated for specific operational purposes, making it the correct choice in this context.