What substance is needed for a fire to burn according to the fire triangle?

The fire triangle consists of three essential elements needed for combustion: fuel, heat, and oxygen. Oxygen is a crucial component, as it supports the chemical reactions that occur during a fire. Without oxygen, the fire cannot sustain itself, even if fuel and heat are present. In the context of the fire triangle, oxygen acts as the oxidizing agent that combines with the fuel to release energy in the form of heat and light. Each of the other options listed does not serve this fundamental role in the combustion process. Gasoline, water, and aerosols may be involved in various interactions with fire, but only oxygen is a necessary and constantly required element for a fire to ignite and continue burning. Understanding the role of oxygen helps firefighters and those in the field to effectively manage fire suppression tactics by removing or limiting oxygen to extinguish fires.