A nurse notices smoke coming from a client's room and discovers a fire in the wastebasket. After moving the client to safety, which of the following is the priority action?

A. Turn off oxygen sources. After ensuring the client is safe, the priority is to reduce the risk of fire spreading, and oxygen greatly increases flammability. Turning off oxygen is a critical safety measure to prevent rapid combustion. B. Put out the fire with an extinguisher. While extinguishing the fire is important, it should only be attempted if safe to do so and after addressing immediate dangers, such as oxygen sources and client safety. C. Close the fire doors on the unit. This is part of containment under the RACE protocol (Rescue, Alarm, Contain, Extinguish), but it is not the first priority after rescue when oxygen is actively feeding the fire. D. Notify the facility operator. This step corresponds to the "Alarm" phase of RACE and is essential for initiating the emergency response. However, it follows immediately after ensuring client safety and environmental hazard reduction, like turning off oxygen.