Explanation: A vessel on a voyage from Miami to Houston will transit through various GMDSS Sea Areas depending on its proximity to shore and the coverage of Digital Selective Calling (DSC) coast stations. * **Sea Area A1** is within the range of at least one VHF-DSC coast station (typically 20-30 nautical miles). The vessel will be in A1 when near Miami, Houston, and other coastal areas along its route. * **Sea Area A2** is beyond A1 but within the range of at least one MF-DSC coast station (typically up to 100 nautical miles). If the vessel ventures further offshore but remains within MF range, it will be in A2. * **Sea Area A3** is beyond A1 and A2, but within the coverage of an Inmarsat geostationary satellite (virtually worldwide between ~70°N and ~70°S). The Gulf of Mexico is well within Inmarsat coverage, so if the vessel goes far enough offshore to be out of MF-DSC range, it will be in A3. Since the precise boundaries of A1 and A2 are determined by the actual range of coast stations, and a vessel's route can vary, it's possible for the vessel to transit through any of these areas during the voyage. Therefore, all options (A1, A2, or A3) may be correct depending on the specific route taken and the extent of coast station DSC coverage.