The light characteristic of composite group flashing (2 + 1) is used in the Aids to Navigation System on the Western Rivers for lights on __________.

Correct Answer: Option A — preferred-channel buoys

Under 33 CFR 62.51, composite group flashing (2+1) lights are reserved for preferred-channel buoys on Western Rivers. This characteristic indicates a junction or bifurcation where the preferred channel is designated by the color of the topmost band.