What is the key operational difference between AIS and DSC on a VHF radio?

A. DSC and AIS use the same channel and cannot be operated simultaneously

B. AIS replaces DSC for distress alerting on modern vessels

C. AIS requires a VHF licence; DSC does not

D. AIS continuously and automatically broadcasts vessel identity, position, course, and speed on Ch 87B/88B — it is one-way broadcast. DSC is two-way digital messaging on Ch 70 for specific alerts (distress, individual calls) — it requires deliberate operator action

A. To send a digitally coded distress alert containing the vessel's MMSI and position automatically to all DSC-equipped stations and the Coastguard

B. To broadcast weather forecasts to other vessels

C. To make telephone calls from the vessel to shore

D. To operate the radar system remotely

A. A GPS waypoint identifier used in coastal navigation

B. Maritime Mobile Service Identity — a unique 9-digit number identifying the vessel; without it a DSC distress alert cannot identify the vessel to rescuers

C. A VHF channel number allocated by Ofcom for distress use only

D. A vessel survey certificate number required by the MCA