Which type of fire requires a Class K fire extinguisher for effective control?

A Class K fire extinguisher is specifically designed to combat fires that involve cooking oils and fats, which are commonly found in commercial kitchens and residential deep-frying situations. These types of fires can reach very high temperatures and can be particularly challenging to extinguish with standard fire extinguishers. The Class K extinguishing agents, often potassium-based, work effectively by saponifying the oils, forming a layer of foam that helps to smother the fire and prevent reignition.

When it comes to the other options: electrical fires require a Class C extinguisher, which is specifically designed to handle fires caused by electrical equipment. Wood fires are typically addressed with Class A extinguishers, as these are meant for ordinary combustibles. Lastly, fires involving plastics may be best handled with Class A or B extinguishers depending on the type of plastic; they do not necessitate a Class K extinguisher. Thus, the Class K extinguisher is uniquely suited for cooking oil fires, making it the correct choice in this context.