Which of the following region lies outside Sea Areas A1, A2, and A3?

Correct Answer: Option D — Sea Area A4

Sea Area A4 encompasses all regions outside the coverage of Inmarsat satellites and terrestrial MF/HF DSC stations, primarily the polar regions. Vessels operating in these high latitudes must carry specialized equipment, such as HF radio, to maintain distress alerting capabilities where satellite and coastal coverage is unavailable.