Explanation: VHF marine radio channels are specifically designated by international and national regulations (like those from the FCC) to ensure safety and efficient communication. Channel 16 (156.800 MHz) is the international calling and distress frequency. All vessels required to carry VHF radio must monitor this channel. Channel 70 (156.525 MHz) is exclusively reserved for Digital Selective Calling (DSC), an automated system for sending distress alerts and calling other stations. Channel 13 (156.650 MHz) is designated for bridge-to-bridge communication, primarily for navigation and safety exchanges between vessels, especially in busy waterways. Therefore, option A correctly identifies these critical channels and their associated frequencies for their respective operations. The other options are incorrect because they misidentify the designated channels for calling/distress or DSC communications.