Fire Extinguisher Certification

I took a test re-certification, and I Apparently she responded incorrectly, or I have not read it right or flew in the exams too quickly ...
With a Class C fire, after cutting the electricity What kind of fire extinguisher if you are using?

You can use a fire extinguisher class C or CO2 extinguisher or other of these would put a class C fire

only use a class C .............


Class C fires involve electrical equipment, such as appliances, wiring, circuit breakers and outlets. Never use water to extinguish class C fires - risk of electrical shock is far too great! Class C extinguishers have a numerical rating. The C classification means the extinguishing agent is non-conductive