What is required to supply the activation energy needed for combustion?

In combustion, activation energy is the initial energy that is needed to start the combustion process. This energy is typically supplied in the form of heat. The auto ignition temperature refers to the minimum temperature required for a substance to ignite without an external spark or flame. When a material reaches this temperature, it can spontaneously ignite due to the energy present in the environment.

Choosing auto ignition temperature as the answer highlights the understanding that, once a material's temperature reaches this specific point, it will have enough energy to begin the oxidation process that characterizes combustion, ultimately leading to the release of heat and light. This concept is critical when discussing fire prevention and control since knowing the auto ignition temperature helps firefighters manage materials that are at risk of ignition.

In contrast, options related to air circulation, heat sources, or supplemental fuel contribute to combustion in different ways, such as facilitating the fire once it is ignited, but they do not directly represent the activation energy necessary for the start of combustion.