In the U.S. Aids to Navigation System on the Western Rivers, a preferred channel buoy to be left to port while proceeding downstream will __________.

Correct Answer: Option D — All of the above

On Western Rivers, preferred channel buoys follow specific conventions. A buoy indicating a preferred channel to be left to port when proceeding downstream is red-topped, displays a red light, and utilizes a composite group flashing (2+1) characteristic to distinguish it from standard lateral marks.