Explanation: On-scene communications for safety-related activities, such as coordinating a rescue, a tow, or other assistance between vessels, should primarily be conducted on VHF Ch-06. This is the internationally recognized intership safety channel, specifically designated for ship-to-ship communication during maneuvers or assistance operations. VHF Ch-16 is the international distress, safety, and calling channel. While initial contact or a distress call might be made on Ch-16, stations are expected to switch to a working channel like Ch-06 to keep Ch-16 clear for new distress calls and urgent safety traffic. Therefore, "Ch-16/06" represents the standard procedure: call on 16, switch to 06 for on-scene work. Other options are incorrect: * **406 MHz** is the frequency used by EPIRBs (Emergency Position Indicating Radio Beacons) to transmit distress alerts to satellites, not for voice communication. * **VHF Ch-22A** is a US Coast Guard working channel, primarily used for communications between the public and the Coast Guard, not for direct intership on-scene coordination. * **VHF Ch-70** is exclusively for Digital Selective Calling (DSC) and is not used for voice communication.