The three main ingredients for an ordinary fire are:

• A. Fuel Source, Heat Source, and Oxygen
• B. Fuel Source, Heat Source, and Nitrogen
• C. Fuel Source, Water, and Oxygen
• D. Heat Source, Oxygen, and Carbon Dioxide

Answer: (A)

Fire needs three things to start and keep burning: a fuel to react, heat to keep the reaction going, and an oxidizer to enable the combustion. In everyday fires, the oxidizer is oxygen from the air, and the fuel can be anything that can burn, like wood, gas, or oil. If you remove any one of these—cool the fuel so it won’t ignite, remove the fuel, or block the oxygen—the flame goes out.

Choosing nitrogen isn’t enough to sustain burning because nitrogen is relatively inert in normal combustion. Water isn’t a fuel; it can cool and suppress flames. Carbon dioxide is a product of combustion, not a fuel or oxidizer, and it doesn’t support flame growth. That’s why the combination that truly supports combustion is fuel, heat, and oxygen.