Which of the four extinguishment methods is the most commonly used by firefighters?

The most commonly used extinguishment method by firefighters is to cool the burning material. This technique involves reducing the temperature of the burning substances below their ignition point, effectively stopping the combustion process. Firefighters typically employ water as the primary cooling agent due to its effectiveness at absorbing heat and transitioning from a liquid to a vapor state, which also helps in displacing heat.

Cooling the material is particularly critical because it addresses the heat component of the fire triangle (heat, fuel, and oxygen). By effectively lowering the temperature, firefighters can mitigate the risk of reignition and prevent the fire from spreading. This method is straightforward and can be executed quickly, making it practical in various firefighting situations.

In contrast, while smothering the flames, removing oxygen, and interrupting the chemical chain reaction are valid tactics, they are used in more specific scenarios or as additional strategies in conjunction with cooling. Smothering may not be effective against all types of fires, and removing oxygen or interrupting the chain reaction can be more complex and may involve specialized agents or techniques. Thus, cooling remains the primary method due to its fundamental effectiveness and ease of implementation.