What is a key feature of a buoy that marks a safe passage?

A key feature of a buoy that marks a safe passage is its distinctive color, which indicates navigational rules. Green and red buoys are used in the United States to mark the channels. Specifically, a green buoy typically indicates the left side of the channel when returning from sea, while a red buoy indicates the right side. This color-coding system helps boaters navigate safely, ensuring that they stay within the parameters of the designated passage and avoid hazards. Understanding buoy colors is essential for safe navigation and compliance with maritime regulations.

While other options may refer to features of buoys, they do not represent the primary function of channel markers. For instance, yellow is used for special purposes, such as caution, while flashing lights serve as additional alerts rather than direct navigation aids. Similarly, the shape of buoys, like arrows, can indicate specific information, but it's the color that is fundamental to indicating safe passage.