Which fires can a wet chemical extinguisher effectively combat?

A wet chemical extinguisher is specifically designed to fight Class K fires, which involve cooking oils and fats, typically found in commercial kitchens. The extinguisher works by cooling the flames and, more importantly, forming a layer of foam on the surface of the burning material to prevent re-ignition and effectively smother the fire.

In addition to Class K fires, wet chemical extinguishers can also combat Class A fires, which involve solid combustible materials such as wood, paper, and textiles. The ability to handle Class B fires, which involve flammable liquids, is typically not associated with wet chemical extinguishers. However, wet chemical extinguishers are not effective against Class C (gas fires) or Class D (metal fires) without specific adaptations or variations.

Therefore, the combination of their effectiveness against both Class A fires and the unique Class K fires makes wet chemical extinguishers indispensable in environments that involve cooking and solid materials, supporting the conclusion that the correct option includes both Class A and K fires.