In the North Sea area, you sight a buoy showing a quick white light with 6 flashes, followed by one long flash at 15 second intervals. Which of the four topmarks shown in illustration D030NG below would be fitted to this buoy?

Correct Answer: Option A — A

IALA Region A defines a North Cardinal mark by a quick or very quick light showing 6 flashes followed by one long flash. This characteristic signifies the buoy is positioned to the north of a danger, requiring vessels to pass to the north of the mark.