Which one of the following is true about can buoys?

Can buoys are indeed cylindrical in shape, which is an important characteristic that helps in their identification on the water. The cylindrical shape allows them to be easily spotted from various angles, which is crucial for navigation and ensuring the safety of boaters.

In the context of buoys, their shape, color, and purpose are all designed to convey specific information to mariners. The cylindrical design makes it easier for them to withstand current and maintain stability in the water, helping to mark various navigational points. While can buoys can be painted in various colors based on specific marking systems, they are typically recognized for their shape rather than any specific color coding. This shape differentiates them from other types of buoys, such as nun buoys, which are conical. Their primary function isn't solely to indicate underwater hazards like rocks but often serves a variety of navigational purposes.