Explanation: Following a Digital Selective Calling (DSC) Distress Alert, a voice transmission is a critical follow-on step required by GMDSS (Global Maritime Distress and Safety System) protocols to provide detailed information and establish direct communication for rescue efforts. The automated DSC alert transmits basic information, but the voice message provides human context and confirmation. The voice transmission must include: * **Ship's Name and Call Sign:** Essential for clear identification by responding stations and SAR authorities. * **MMSI number:** The unique digital identifier of the vessel, which links to its registration details. * **Position:** Crucial for search and rescue operations, confirming the location transmitted by DSC. * **Nature of distress:** Specifics about what has happened (e.g., "fire onboard," "sinking," "medical emergency"). * **Assistance requested:** What kind of help is needed (e.g., "medical evacuation," "tow," "firefighting assistance"). This comprehensive information, as presented in **B**, enables search and rescue authorities to quickly understand the situation and coordinate an effective response. Option A is incorrect because the "DSC frequency used" is for the alert itself, not part of the distress message content, and "any other information" is too vague. Option C is incorrect because "Ship's IMN" (Inmarsat Mobile Number) is not a universal primary identifier for DSC (MMSI is), and it omits the ship's name and call sign. Option D similarly misidentifies the primary digital identifier (IMN instead of MMSI) and is vague.