The correct answer is B) class B. Class B fires involve flammable liquids and gases, such as gasoline, oil, and propane. For these types of fires, a blanketing effect is essential to extinguish the fire by depriving it of oxygen. This is typically achieved through the use of foam or carbon dioxide extinguishing agents, which create a barrier that prevents the fuel from continuing to burn. The other options are incorrect because: Class A fires involve ordinary combustible materials like wood, paper, and cloth, which are best extinguished through cooling and smothering methods; Class C fires involve energized electrical equipment, which require non-conductive extinguishing agents; and Class D fires involve combustible metals, which require specialized dry powder extinguishers.