What agency administers civil aviation and regulates air traffic safety?

The U.S. Federal Aviation Administration (FAA) is the agency responsible for administering civil aviation in the United States and regulating air traffic safety. It oversees the management of air traffic control, the establishment of safety protocols, and the certification of pilots and aircraft.

The FAA's role is crucial in ensuring that air travel is safe and efficient. They implement regulations to protect passengers and crew while maintaining suitable levels of air traffic flow. By focusing on aviation safety, the FAA contributes to a system that can effectively respond to various challenges, including those that might arise from national security threats.

The other agencies listed have different primary responsibilities. For example, the Federal Bureau of Investigation is involved in national security, criminal investigations, and counterterrorism, rather than aviation regulation. The Department of Homeland Security focuses on protecting the nation from a variety of threats, which includes aspects of transportation security but does not have direct responsibility for aviation administration. The National Aeronautics and Space Administration primarily deals with space exploration and scientific research, not air traffic safety or civil aviation. Hence, the FAA is the correct choice for this question.