A Class B fire extinguisher is designed to combat fires involving which substances?

A Class B fire extinguisher is specifically designed to combat fires involving flammable liquids and gases, which includes materials such as gasoline, oil, grease, and other combustible liquids. This classification is critical for effective firefighting because using the wrong type of extinguisher can exacerbate the situation. For instance, using a water-based extinguisher, which is ideal for Class A fires involving solid combustible materials like paper and wood, would not be effective on flammable liquids and could even spread the fire.

In contrast, the other options represent different classes of fire. Electrical equipment fires are handled by Class C extinguishers, while paper and wood fires fall under Class A. Thus, understanding the specific applications of each extinguisher type ensures that fire safety measures are both effective and appropriate for the materials involved.