Question 369Navigation General

The correct answer is D) Green buoy with a yellow square. A green buoy with a yellow square topmark indicates a dual purpose buoy, which can be used either as a channel marker or a special purpose buoy. This type of buoy is used to mark areas such as anchorages, boat basins, or other special areas. The yellow square topmark helps distinguish this type of buoy from standard green channel markers. The other answer choices do not represent dual purpose buoys. A red buoy with a horizontal yellow band, a red and white vertically-striped buoy with a red spherical topmark, and a red and white vertically-striped buoy with a vertical yellow stripe are all different types of channel markers or special purpose buoys, but do not indicate a dual purpose buoy.