What are the four main classes of fire?

The classification of fires into four main classes is fundamental for understanding fire behavior and selecting appropriate firefighting methods. In the answer provided, classes A, B, C, and D refer specifically to the types of materials that are burning and the techniques necessary to extinguish them.

Class A fires involve ordinary combustibles like wood, paper, and textiles; they are typically extinguished using water or foam. Class B fires involve flammable liquids and gases, such as gasoline or oil, and require agents like dry chemical or foam suppressants. Class C fires are electrical in nature and should be tackled with non-conductive extinguishing agents, often using dry chemicals specifically designed for electrical hazards. Class D fires involve combustible metals like magnesium or aluminum, which require specialized extinguishing agents, often based on powder to safely extinguish the flames without causing a reactive hazard.

The other options suggest a different numbering or classification system that does not align with established fire classifications or the commonly accepted language used in fire safety. Understanding these classes helps in not only choosing the right type of fire extinguisher but also in preventing accidents related to inappropriate extinguishing methods.