Why: The standard fire classifications recognized by NFPA and most fire safety standards are five main classes: Class A (ordinary combustibles), Class B (flammable liquids), Class D (combustible metals), Class C (energized electrical equipment), and Class K (cooking oils and fats). Class K is specifically for kitchen fires involving vegetable or animal oils and fats. Stating only four classes (A, B, C, K) is incorrect as it omits Class D.

Why: Class B fires involve flammable liquids such as gasoline, oil, grease, and paints, which cannot be extinguished with water as it may spread the fire. Paper and wood are Class A fires, involving ordinary solid combustibles that can be extinguished with water or foam.

Why: Class B fires involve flammable liquids. Aqueous film-forming foam (AFFF) smothers the fire by forming a blanket over the fuel, preventing vapor release. Carbon dioxide (CO2) displaces oxygen and cools the fire. Wet chemical extinguishers are primarily for Class K (cooking oils), not standard for Class B. Thus, D (A and B only) is correct.

Why: NFPA 10 standards require building protection extinguishers to cover common hazards: Class A (ordinary combustibles like wood, paper) and Class B (flammable liquids like fuels). Class C (electrical) is addressed separately where needed, but standard building protection prioritizes A and B for comprehensive coverage.

Why: This answer provides a comprehensive overview meeting 5-mark criteria: introduction, detailed points with examples, and conclusion. It covers all standard classes per NFPA and fire safety standards.