Which of the following best describes a no-fly zone's purpose?

A no-fly zone is primarily established to restrict access to certain areas for safety and security reasons, especially when there are potential hazards such as radiation. These zones are often implemented in locations near nuclear facilities or during incidents involving hazardous materials to protect both the public and the environment from potential exposure to harmful radiation. By prohibiting aircraft from entering these sensitive areas, the no-fly zone helps mitigate the risk associated with possible radiation releases and ensures that emergency response actions can proceed safely without interference.

The other options do not accurately capture the fundamental purpose of a no-fly zone. Facilitating transportation of goods or enhancing traffic management focuses on operational efficiencies in airspace, which are not the primary aims of a no-fly zone. Similarly, allowing for drone testing may be a specific activity permitted under certain conditions, but it does not define the overarching goal of a no-fly zone. Thus, restricting access due to radiation hazards is the most fitting description of a no-fly zone's purpose.