The correct answer is C) Convection. Fire dampers prevent the spread of fire by blocking the spread of fire through convection. Convection is the transfer of heat through the movement of a fluid, such as air or smoke. Fire dampers are designed to close automatically when exposed to high temperatures, creating a barrier that stops the flow of hot gases and smoke, thus preventing the fire from spreading through the ductwork or building via convection. The other answer choices are incorrect because they do not accurately describe how fire dampers function to prevent fire spread. Conduction is the transfer of heat through direct contact, while radiation is the transfer of heat through electromagnetic waves. Neither of these heat transfer mechanisms is the primary way in which fire dampers stop the spread of fire.