Explanation: The Global Maritime Distress and Safety System (GMDSS) integrates various communication technologies. Terrestrial radio techniques involve transmission and reception between stations on Earth's surface, without relying on satellites as relays. VHF-MF-HF-DSC (Very High Frequency, Medium Frequency, High Frequency Digital Selective Calling) represents the terrestrial components of GMDSS. VHF provides short-range, line-of-sight communication. MF extends range using ground waves, and HF allows for long-distance skywave communication via the ionosphere. All these utilize land-based coast stations or ship-to-ship transmissions. DSC is the signaling method used on these bands for automated distress alerting and routine calls. Conversely, Inmarsat-C is a satellite communication system. GPS (Global Positioning System) is a satellite-based navigation system, providing position data. Neither of these utilizes purely terrestrial radio techniques. "F-77" is not a recognized GMDSS system.