A yacht is under sail and its propulsion machinery is not being used. Which Rule 35 signal should it make in restricted visibility?

A sailing vessel whose propulsion machinery is not being used sounds one prolonged followed by two short blasts at intervals of not more than two minutes. If propulsion machinery is being used, the yacht is power-driven for the Rules. Apply the signal in or near restricted visibility and keep the full lookout and Rule 19 response. Revise Fog Signals (Rule 35).