What sound signal should be used by every other vessel that is not power-driven?

Answer: B — One long blast followed by two short blasts

The use of sound signals by vessels that are not power-driven is outlined in the COLREGs, specifically under rule 35 concerning sound signals in restricted visibility. The correct answer involves the use of one long blast followed by two short blasts, which is a signal that indicates that a vessel is engaged in a specific maneuver or is communicating its intentions to other vessels around it. This sequence of sound signals serves to provide a clear indication to other vessels that are nearby, especially in situations where visual signals may not be adequate due to restrictions in visibility or distance. The long blast serves to alert other vessels, while the two short blasts provide further clarity about the nature of the maneuvering vessel's intentions. It is important to note that vessels that are not power-driven include sailing vessels, fishing boats, and others that may not generate their own propulsion. These vessels still have the responsibility to communicate effectively with surrounding traffic to ensure safety on the water. The sound signal prescribed in this situation helps prevent collisions by providing an audible cue to others regarding the vessel’s possible actions or status.