Which of the following is NOT a class of fire extinguisher?

In the context of fire extinguishers, classes are determined based on the types of fires they are designed to combat. Class A extinguishers are used for ordinary combustibles such as wood, paper, and textiles. Class B extinguishers are meant for flammable liquids like gasoline, oil, and greases. Class D extinguishers are specifically designed for fires involving combustible metals, such as magnesium and sodium.

Class E, however, is not an officially recognized class of fire extinguisher. While there are many informal classifications used to describe different types of fire hazards and corresponding extinguishers, official classifications typically do not include Class E. Therefore, confirming the absence of Class E from recognized fire extinguisher classifications makes it clear that this option stands apart from the others.