Explanation: GMDSS (Global Maritime Distress and Safety System) requirements for equipped ships are comprehensive, ensuring safety at sea. Option D correctly identifies these core functions: * **Transmit distress alerts:** A primary function, enabling a ship in distress to alert rescue authorities and nearby vessels (e.g., via DSC, EPIRB). * **SAR (Search and Rescue) and on-scene communications:** Facilitates coordinated rescue efforts and communication among vessels involved in a SAR operation (e.g., using SARTs, VHF/MF/HF voice). * **MSI (Maritime Safety Information):** Receiving critical weather forecasts, navigation warnings, and other safety broadcasts (e.g., via NAVTEX, SafetyNet). * **Bridge-to-Bridge and general radio communications:** Essential for routine operational communication, collision avoidance, and port operations. Option A is incorrect because "receipt of satellite alerts from other vessels" is primarily a function of Coast Earth Stations and Rescue Coordination Centers, not generally a direct communication function for another GMDSS ship (though ships *do* receive relayed distress alerts). Option B is incomplete ("relay of" what?). Option C includes "RDF of EPIRB homing signals," which, while helpful, isn't mandated as a core *communication function* in the same way distress alerting or MSI receipt is for the ship itself.