Which characteristic describes daymarks that are nun buoys?

Nun buoys are designated as traditional navigational aids used primarily in marine navigation. They are typically marked by a red color and have a triangular shape, which makes them easily identifiable on the water. This characteristic is essential for mariners, as these buoys indicate the right side of a channel when approaching from the open sea or heading upstream. The red color, combined with the triangular shape, serves to visually communicate to boaters the appropriate side to keep on their starboard (right) side, enhancing safety and navigation efficacy.

The other options do not accurately describe nun buoys. For instance, green shapes generally signify can buoys, which serve a different purpose and are positioned on the opposite side of the channel. Odd numbers are typically marked on red nun buoys, but this characteristic is not included in the primary description of a nun buoy itself. Circular shapes with blue coloring are often associated with informational or regulatory markers rather than navigational buoys like nun buoys. Thus, the description of the red, triangular shape is what clearly identifies nun buoys in North American navigation.