Where can regulations regarding U.S.-flag vessels' GMDSS be found?

The correct answer is that regulations regarding U.S.-flag vessels' GMDSS can be found in 47 CFR Part 80. This section of the Code of Federal Regulations encompasses the rules governing the use of radio equipment on ships, which includes the Global Maritime Distress and Safety System (GMDSS).

The inclusion of GMDSS regulations in Part 80 illustrates the U.S. government's commitment to maritime safety and communication standards, ensuring that vessels are equipped with the necessary technology and protocols for distress situations and safety communication at sea.

While other options reference related materials or organizations, they do not provide the correct regulatory framework. For instance, CCIR #476 relates to the international radio regulations but does not specifically address U.S. regulations for GMDSS on U.S.-flag vessels. The reference to FCC Part 83 does not correspond to the relevant provisions for maritime mobile communications. Lastly, stating that regulations are published only by the U.S. Coast Guard overlooks the comprehensive regulatory framework established by the FCC, which governs maritime communications, making the first option the most accurate and relevant choice for U.S.-flag vessels' GMDSS regulations.