USCG Firefighting License Practice Exam

The correct answer is oxygen because fire requires three main elements to ignite and sustain combustion, commonly referred to as the fire triangle: fuel, heat, and oxygen. When oxygen is removed from the equation, combustion ceases, and the fire can be extinguished.

In practical firefighting, this is often achieved through various methods, such as smothering the fire with a blanket or foam, using a fire extinguisher that displaces oxygen, or spraying the fire with water to cool down the surroundings and limit the available oxygen.

While nitrogen is abundant in the atmosphere and is an inert gas that does not support combustion, removing it does not have a direct effect on extinguishing a fire. Sodium and carbon dioxide, while they have their roles in chemical processes and fire suppression mechanisms, do not represent the fundamental element necessary for maintaining a fire. Removing oxygen remains the most effective means of extinguishment in a fire scenario.