Explanation: Sea Area A-1, under the Global Maritime Distress and Safety System (GMDSS), is precisely defined as an area within the range of at least one VHF-DSC coast station. Therefore, option B is correct because to be considered within Sea Area A-1, a vessel must continuously maintain the capability to communicate via VHF-DSC with a shore station. Option A is incorrect because Sea Area A-1 is defined by VHF-**DSC** coverage, not by the ability to communicate on VHF Channel 16 for voice. While Ch-16 is a distress frequency, DSC is the primary alerting method for GMDSS. Option C is incorrect. VHF-DSC coverage is generally limited to 20-30 nautical miles due to line-of-sight constraints. A vessel 40 nm offshore would likely be outside reliable A-1 coverage, making the statement that all coastal voyages "always" have A-1 DSC coverage false. Option D is incorrect. MF-DSC (Medium Frequency Digital Selective Calling) defines Sea Area A-2, not Sea Area A-1.