Explanation: After an initial "hot-key" Distress alert via Digital Selective Calling (DSC), which typically transmits the vessel's Maritime Mobile Service Identity (MMSI), position, and the nature of distress, a detailed follow-up voice message is essential. This detailed message provides crucial information not conveyed by the automated alert, allowing rescuers to plan and execute an effective response. * **Vessel name & call sign:** These are critical for voice identification, confirming the distressed vessel's identity, and for any visual confirmation. The DSC alert sends the MMSI, not the name or call sign directly. * **POB (Persons On Board):** Knowing the number of people requiring rescue is paramount for search and rescue operations, influencing resource allocation. This is not included in the initial DSC alert. * **All potential means to communicate with the vessel:** While the DSC alert might suggest a default voice channel (e.g., VHF Channel 16), providing other frequencies (VHF, HF) or alternative contact methods (e.g., satellite phone) offers critical redundancy and flexibility for rescuers trying to establish contact. Options A, B, and D are incorrect because they largely include information (vessel position, nature of distress, MMSI) already transmitted in the initial DSC "hot-key" alert, or omit other vital details necessary for a comprehensive follow-up message.