Which of the following is an example of a special mark buoy?

The correct choice identifies a special mark buoy, which is designed to convey information about specific features or areas rather than providing navigational guidance typical of other buoy types. A buoy marking a swimming area serves as a special mark because it indicates a zone where certain activities, such as swimming, are allowed while keeping vessels at a safe distance.

Special mark buoys are usually shown as yellow in color and may be equipped with specific day shapes or lights to clearly communicate their purpose. This differentiation helps to ensure safety by indicating areas that are important for public use, while also advising mariners to take caution in those zones.

Other buoy types, such as those marking channel edges or safe water, serve more traditional navigational functions. The distinction is clear in that while the other options communicate navigational information, the swimming area buoy speaks specifically to user access and safety in that part of the water, making it a relevant example of a special mark buoy.