If individual sprinkler heads cannot be shut off, what should be done to stop the flow of water?

The correct response involves closing the sprinkler control valve because this action effectively stops the flow of water to all the sprinkler heads connected to that specific valve. Sprinkler systems are designed with control valves that regulate water flow; by closing this valve, the water supply to the sprinkler heads is interrupted, thereby preventing further discharge of water. This is a critical step during a fire incident when individual heads cannot be manually adjusted, and it helps in minimizing water damage while the fire suppression system operates.

The other options suggest methods that either do not directly address controlling the water flow or may even exacerbate the situation. Crimping the piping in the riser could potentially cause structural damage and is generally not recommended as a method of stopping water. Opening the fire department connection outside does not stop water flow; rather, it allows access for firefighters to connect their hoses for external water supply. Lastly, activating more heads using a mechanical heat source is counterproductive as it leads to additional water flow and actively diminishes the effectiveness of controlled suppression efforts.