The typical operating range of automatic identification systems (AIS) at sea is nominally __________.

Correct Answer: Option C — 20-25 nm

AIS operates in the VHF maritime band, typically utilizing line-of-sight propagation. While range can vary based on antenna height and atmospheric conditions, the nominal operating range for ship-to-ship AIS communication is generally accepted as 20 to 25 nautical miles, consistent with standard VHF radio propagation characteristics at sea.