Explanation: When a vessel receives a Digital Selective Calling (DSC) Distress relay on VHF Channel 70, it signifies that a distress alert has been issued. Channel 70 is exclusively for DSC alerts and calls, not for voice communications. The international regulation for maritime distress communications dictates that after a DSC alert, actual voice distress traffic will occur on the dedicated voice distress channel. Therefore, the watch officer's immediate action should be to monitor **VHF Channel 16 (B)**. Channel 16 is the international voice distress, urgency, and safety channel. The distressed vessel, or the station relaying the distress, will typically follow up a DSC alert with a voice "Mayday" or "Mayday Relay" call on Channel 16 to provide further details and coordinate assistance. **A) Retransmitting the DSC call on Ch-70** is generally unnecessary unless specifically directed or if there's reason to believe the original relay was not widely received. It can clutter the DSC channel. **C) Monitoring Ch-06** is incorrect as Ch-06 is a ship-to-ship safety channel, not the primary distress voice channel. **D) Transmitting a voice "Mayday Relay" call on Ch-13** is incorrect because Ch-13 is the Bridge-to-Bridge navigational safety channel, not for distress relays. Additionally, the first action after receiving a relay is typically to listen, not transmit, unless directly involved in rendering assistance or if further relays are necessary.