Final answer:
The Federal Communications Commission (FCC) governs radio transmissions and is responsible for regulating interstate communications by radio, television, wire, satellite, and cable in the United States.
Step-by-step explanation:
The agency that governs radio transmissions is the Federal Communications Commission (FCC). The FCC is an independent agency of the United States government that regulates interstate communications by radio, television, wire, satellite, and cable in all 50 states. It is responsible for assigning frequencies, regulating broadcasting content, and ensuring compliance with regulations.