What signaling devices must a vessel between 20 to 100 meters have?

Answer: A — Whistle and bell

A vessel between 20 to 100 meters in length is required to have specific signaling devices to ensure safe navigation and compliance with the COLREGs. The correct answer indicates that such a vessel must carry a whistle and a bell. The whistle serves as an essential device for signaling audible warnings to other vessels, especially in situations of limited visibility or to indicate intentions such as changing course. The bell serves a similar purpose, primarily for maneuvering or during foggy conditions, to alert nearby vessels to its presence. Having both these devices ensures that the vessel can effectively communicate with other maritime traffic, enhancing safety on the waters. Other signaling devices that could be mentioned in other contexts, like a foghorn, may not be a strict requirement for this size category under the COLREGs. Therefore, focusing on the whistle and bell specifically adheres to the regulations set forth and addresses the requirements adequately for vessels in this size range.