What type of extinguisher is designed to extinguish class B-C fires?

A carbon dioxide extinguisher is specifically designed to extinguish Class B and C fires, making it the correct choice. These types of extinguishers work by displacing oxygen, which is crucial for combustion, and they are particularly effective on flammable liquids (Class B) and electrical fires (Class C).

Class B fires involve flammable liquids such as oils, gasoline, and solvents, while Class C fires encompass fires involving energized electrical equipment. Using a carbon dioxide extinguisher on these types of fires is safe and effective because it does not conduct electricity and leaves no residue, minimizing damage to both equipment and the environment.

In contrast, foam extinguishers are primarily used for Class B fires by creating a barrier between the fuel and the oxygen, but they are not suitable for electrical fires. Dry powder extinguishers can also be used on both Class B and C fires, but they are not exclusive to them. Water extinguishers are ineffective against Class B fires and can be dangerous against Class C fires, as water can conduct electricity and potentially cause electrocution. Thus, the selection of a carbon dioxide extinguisher as the best option indicates a clear understanding of fire types and the appropriate extinguishing methods.