In the North Sea area, you sight a buoy showing a quick white light with 9 flashes every 15 seconds. Which of the four topmarks shown in illustration D030NG below would be fitted to the buoy?

Correct Answer: Option C — C

A quick white light with 9 flashes every 15 seconds identifies a West Cardinal mark under IALA buoyage rules. The topmark for a West Cardinal mark is two cones pointing toward each other (apex to apex). This configuration is depicted as illustration C in the standard IALA buoyage reference diagrams.