Fire extinguishers work by removing one or more of these elements of fire: ________, oxygen and fuel.

Fire extinguishers are designed to combat fire by targeting the fundamental elements that are necessary for a fire to sustain itself. The three primary elements of the fire triangle are heat, oxygen, and fuel. By eliminating one or more of these components, a fire can be extinguished.

Choosing heat as the correct element reflects an understanding of how extinguishing agents operate. Many fire-extinguishing mechanisms work by cooling the fire's temperature below the combustion threshold, thereby removing heat from the equation. This is typically achieved through various extinguishing substances, such as water or chemical agents that can absorb heat.

Other elements like argon, electricity, and water do not function in the same capacity as heat does in the context of extinguishment. Argon is an inert gas that does not actively combat fire in the sense required here. While water can be an effective extinguishing agent by both cooling and smothering, it is not one of the three vital components of fire itself, which makes heat a more accurate answer in the context of this question.