Aircraft can't fly in or over which type of airspace?

The correct answer is that aircraft are prohibited from flying in or over restricted airspace. Restricted airspace is designated for specific purposes, such as military operations, and is typically established to ensure safety and security. Within this airspace, there are flight restrictions and certain conditions that must be met for access. This can include the need for prior authorization from the controlling authority, which may not always be granted. Violating the boundaries of restricted airspace can lead to serious consequences, including potential safety hazards and legal repercussions.

Other airspace classifications, such as Class G, Class C, and Class D, allow for flight under certain conditions and with established communication protocols. Class G is uncontrolled airspace with minimal restrictions, while Class C and D airspaces have specific communication requirements and traffic management to safely accommodate aircraft operations.