Which statement about CO2 portable extinguishers is accurate?

• A. Used for class B and C fires and displaces oxygen.
• B. Leaves a lot of residue on electrical equipment.
• C. Not suitable for electrical fires.
• D. Can be used safely in a small enclosed room without exiting.

Answer: (A)

CO2 extinguishers work by displacing the surrounding air, effectively limiting the oxygen available to feed the fire. That smothering action makes them well suited for electrical fires (class C) and many flammable-liquid fires (class B). The statement is best because it highlights the key mechanism—oxygen displacement—and correctly identifies the fire types where CO2 is used. Additionally, CO2 has the advantage of leaving little to no residue on equipment, which is another reason it’s preferred for electrical devices. However, using CO2 in a small enclosed room with people present is unsafe because the rapid release of gas can create an asphyxiation risk, so occupants should evacuate before discharge.