Which of the following is the agency responsible for regulating all US air carriers?

The Federal Aviation Administration (FAA) is the agency responsible for regulating all US air carriers. This includes overseeing civil aviation safety, establishing regulations and standards, providing air traffic control services, and managing the US airspace. The FAA's authority extends to both commercial and general aviation, ensuring that air carriers comply with safety regulations that protect passengers and cargo during operations.

The FAA plays a critical role in maintaining high safety standards across the aviation industry. Its oversight responsibilities include the certification of aircraft, pilots, and the operators themselves, as well as enforcing regulations related to the operation of air carriers. This comprehensive regulatory framework is essential for promoting a safe and efficient aviation environment in the United States.