With which sound signal equipment must a vessel of 12 meters or more in length that is operating in inland waters be provided?

A vessel that is 12 meters or more in length operating in inland waters is required to be equipped with a whistle as its sound signal equipment. The whistle serves as an important tool for communication and navigation safety, especially in situations where visual signals might not be effective. It is used to indicate the vessel's presence to others, warn of danger, and convey intentions, especially in busy or confined waterways.

The use of a whistle is compliant with the Inland Navigation Rules, which outline the necessary equipment for vessels to ensure safe operations, particularly in situations with limited visibility or during encounters with other vessels. The whistle can produce sound signals audible over a significant distance, which is essential for alerting nearby vessels and ensuring safe navigation.

While other sound signal devices, like bells and horns, may also be used in various contexts, the specific requirement for a vessel of this length under Inland Rules is the whistle, making it the appropriate choice for this question.