Explanation: The Global Maritime Distress and Safety System (GMDSS) fundamentally aims to ensure maritime safety through enhanced communication. **A) Every vessel must be able to perform communications functions essential for its own safety and the safety of** (other vessels and shore stations). This is the core principle of GMDSS. It mandates that compulsory vessels carry specific equipment and adhere to procedures to ensure they can initiate and receive distress alerts, transmit safety information, and conduct general communications vital for their own safety and to assist others. This capability is central to the system's design. **B) Vessels must transmit a DSC distress relay upon receipt of a DSC distress alert.** This is incorrect. Vessels generally should *not* relay a DSC distress alert automatically unless they have confirmed the alert has not been received by a shore station (Coast Guard/RCC) or are directed to do so. Unnecessary relays can clutter the system. **C) Only the vessels closest to a Distress incident must render assistance.** This is incorrect. While proximity is a factor, the international SOLAS convention states that the master of any ship at sea is bound to proceed to the assistance of persons in distress if informed of their need. **D) Vessels must immediately acknowledge all DSC distress alerts.** This is incorrect. Acknowledging a DSC distress alert is primarily the responsibility of a shore station. Other vessels should typically only acknowledge if they are involved in the rescue, instructed to do so, or have established voice contact with the distressed vessel. Immediate, uncoordinated acknowledgments can interfere with proper distress management.