Which type of day mark is equivalent to a nun buoy?

The correct choice is that red triangles with even numbers are equivalent to a nun buoy. In the system of aids to navigation, nun buoys are used to mark the right side of a channel when approaching from the waterway's sea or upstream direction. The red color signifies that the mark is on the right side of the navigable channel, and the triangular shape helps to visually distinguish it from other types of marks.

The even numbering system provides a standardized way to identify nun buoys, ensuring that boaters can easily recognize and navigate using these aids. This uniformity aids safety and helps prevent confusion while on the water.

While the other options describe different types of navigational aids, they do not align with the characteristics of nun buoys. Each type of day mark has specific features, such as color and shape, that help boaters interpret their function and location in relation to navigable waters.