What do junction buoys that are red and green indicate?

Junction buoys that are colored red and green are specifically designed to indicate to boaters which channel is the preferred route when a channel splits. The red buoy typically signifies the right side of the channel when entering from the sea or headed upstream, while the green buoy represents the left side. When approaching a junction, seeing these buoys will guide the boater in choosing the appropriate path to continue safely on their journey.

The other options, while valuable concepts regarding boating safety and navigation, do not pertain to the function of junction buoys. The note regarding fog signaling primarily addresses visibility measures rather than channel designation, no-wake zones focus on speed restrictions for safety, and navigation change warnings relate to potential hazards or alterations in the waterway, not channel determinations.