Which of the following are the classes of fire extinguishers recognized in firefighting?

The correct answer identifies the classes of fire extinguishers as A, B, C, D, and K. Each class represents different types of fires and the appropriate extinguishing agents for those fires, which is crucial for effective firefighting.

Class A extinguishers are designed for ordinary combustible materials such as wood, paper, and cloth. Class B extinguishers are used for flammable liquids, including gasoline, oil, and grease. Class C extinguishers are suitable for electrical fires where electricity is involved. Class D extinguishers are meant for fires involving combustible metals, such as magnesium or sodium, which require specific agents to extinguish. Lastly, Class K extinguishers are specifically designed for kitchen fires involving cooking oils and fats, making them essential for commercial kitchens and restaurants.

Understanding these classes allows firefighters to choose the correct extinguisher to combat a specific type of fire effectively, ensuring safety and efficiency during firefighting operations. The other options either include incorrect classifications or combine classes that do not exist within recognized firefighting standards.