GMDSS is primarily a system based on?

The Global Maritime Distress and Safety System (GMDSS) is primarily designed to enhance maritime safety through effective communication between ships in distress and search and rescue authorities. The system utilizes various technologies and methods to ensure distress signals can be transmitted promptly, enabling rescue operations to be coordinated efficiently.

The correct answer emphasizes the connection established between search and rescue authorities and vessels that are in need of help. This linkage is crucial for timely intervention in emergencies, demonstrating the systematic approach the GMDSS employs to streamline communications for safety at sea. By integrating various communication methods, the GMDSS allows for rapid and reliable contact between distressed vessels and the appropriate response agencies.

The other options mention specific technologies or methods used in maritime communication, such as radiotelephony or digital selective calling, but they do not encapsulate the overarching goal of the GMDSS, which is to link distressed ships directly with rescue services. This context is vital for understanding the system's primary function in promoting maritime safety.