What is the term for the substance that puts out the fire?

The correct term for the substance that puts out a fire is "extinguishing agent." Extinguishing agents are materials specifically designed to suppress or extinguish flames during a fire incident. They work by various mechanisms, such as removing heat, starving the fire of oxygen, or suppressing the chemical reaction of combustion.

Understanding the role of an extinguishing agent is crucial for firefighters, as it informs the choice of tools and materials used in firefighting operations. For example, water is a common extinguishing agent that cools the flames, while foam can smother a fire by cutting off its oxygen supply.

The other terms listed do not accurately describe a substance that puts out a fire. "Live load" refers to the weight of occupants and movable objects in a building, "propellant" typically pertains to a substance that drives something forward, such as in firearms or aerosol cans, and "dry charge" generally refers to the storage of energy in batteries or mechanisms, not to firefighting contexts. Therefore, the term "extinguishing agent" is the most appropriate choice for this question.