The correct answer is D) All of the above. The spread of fire is prevented by shutting off the oxygen supply, cooling surfaces adjacent to the fire, and removing combustibles from the endangered area. These three actions work together to control the fire triangle (fuel, heat, and oxygen) and stop the fire from spreading. Shutting off the oxygen supply deprives the fire of one of its essential elements. Cooling the adjacent surfaces prevents the fire from spreading through conduction. Removing combustibles from the area eliminates potential fuel sources. Employing all three of these methods is the most effective way to prevent the further spread of a fire.