Which agency regulates all radio operations in the United States?

The correct choice is the Federal Communications Commission (FCC), which is the agency responsible for regulating all forms of communication in the United States, including radio operations. The FCC oversees the licensing of radio frequencies, ensures that communications are conducted fairly and in accordance with the law, and manages the airwaves to minimize interference between different users. This includes both commercial and private radio operations, providing a structured environment for broadcasting and communication services.

The other agencies listed have different areas of focus. The Federal Aviation Administration (FAA) primarily regulates civil aviation, including the safety of aircraft and air traffic; it does not oversee radio communication unrelated to aviation. The Federal Bureau of Investigation (FBI) is a national security and law enforcement agency, focusing on investigations and criminal justice, rather than communications regulations. The National Highway Traffic Safety Administration (NHTSA) works on improving road safety and regulating vehicle standards, which is outside the scope of radio operations and communications.