What sound signals should vessels not under command use?

Answer: B — Two prolonged blasts at intervals of not more than one minute

Vessels not under command are required to use two prolonged blasts at intervals of not more than one minute to indicate their condition to other vessels. This signal serves to alert nearby boats that the vessel is unable to maneuver as a result of engine failure, steering problems, or other issues. The prolonged blasts are meant to convey the vessel's status clearly and help prevent collisions by ensuring that other vessels in the vicinity are aware of the situation. The option reflecting the requirement for sound signals serves to enhance safety on the water, as it communicates essential information about a vessel's operational state. The specific interval of not more than one minute also emphasizes the need for timely notifications to other vessels, reducing risks associated with navigation in crowded or challenging waterways.