Areas where operations are hazardous to nonparticipating aircraft and contain airspace within which flight is subject to restrictions are known as _____________.

The correct choice is "Restricted Areas." These are specific zones in the airspace that impose limitations on aircraft operations to ensure safety. Restricted Areas are created to protect the public and other aircraft from potentially hazardous activities, such as military exercises or hazardous material testing.

In these areas, flight operations are subject to restrictions that may include altitude limitations and the requirement for prior permission to enter. The primary goal is to create a safe environment for nonparticipating aircraft by controlling access to areas where operations may pose a danger.

The other types of airspace (like Prohibited Areas, Advisory Areas, and Controlled Areas) serve different purposes. Prohibited Areas completely restrict entry for all aircraft without exception, which is not the intent of Restricted Areas where permission may be granted. Advisory Areas provide information but do not impose restrictions, while Controlled Areas are designated for air traffic control oversight but do not inherently indicate hazards.