Under the U.S. Aids to Navigation System, a yellow buoy may be used to mark what?

In the U.S. Aids to Navigation System, yellow buoys specifically indicate areas that are associated with certain activities or hazards. One primary use of a yellow buoy is to mark fishing equipment, including fish nets, which helps to alert mariners to the presence of these potentially hazardous obstructions in the water. This use is important for navigation safety, as it allows vessels to avoid running over or getting tangled in fishing gear, which can pose dangers to both the boat and the nets themselves.

While a yellow buoy can also be equipped with lights, such as a white light, or possibly be associated with specific marking systems, the direct and acknowledged function of a yellow buoy in this context is its application to marking fishing equipment or related areas. Therefore, the most accurate selection regarding what a yellow buoy may mark is the area associated with fishing nets.