Which extinguishing agent is commonly used to fight Class-A fires?

Water or soda acid is correctly identified as a commonly used extinguishing agent for Class A fires. Class A fires involve ordinary combustibles such as wood, paper, cloth, and some types of rubber and plastics. Water is particularly effective in this context because it cools the burning materials and reduces the temperature below their ignition point, effectively extinguishing the fire.

Soda acid, often used in historical fire extinguishers, is a solution that produces carbon dioxide when it reacts with acid, helping to smother the fire. The cooling effect of water combined with the smothering action of soda acid makes them suitable for the Class A category. In contrast, other agents like carbon dioxide and dry powder are better suited for different types of fires, such as those involving flammable liquids or electrical fires, and foam is generally used for Class B fires, which involve flammable liquids.