How does a dry chemical extinguisher work?

A dry chemical extinguisher works by interrupting the fire triangle, which consists of fuel, heat, and oxygen. The primary active agent in a dry chemical extinguisher is usually a powder, such as monoammonium phosphate, which can chemically react with the fuel involved in the fire. When discharged, the powder blankets the fire, not only suffocating it by separating the fuel from oxygen but also chemically interfering with the combustion process itself. This means that it disrupts the reactions taking place that sustain the fire, effectively extinguishing it.

While other methods like smothering the flames or cooling them can also extinguish fires, they do not encompass the chemical reaction aspect that dry chemical extinguishers provide. Additionally, while displacing oxygen is a method used by other types of extinguishers, it is not the main function of dry chemical extinguishers. The correct answer highlights the unique mechanism by which dry chemical extinguishers effectively combat fires.