Which item can be a source of heat that may cause a fire?

Coffeemakers can be a significant source of heat that may lead to a fire, particularly when left unattended or malfunctioning. These appliances generate heat through their heating elements to brew coffee, which means if they overheat or if there is a buildup of coffee grounds or other materials, it can create a fire hazard. Proper maintenance and supervision are crucial when using such devices to prevent potential fires.

While wooden planks can burn and serve as fuel in a fire, they are not a direct source of heat themselves unless subjected to an external heat source. Flashlights, on the other hand, typically use batteries, which can overheat, but they are not primarily heat-generating devices. An oxygen tank can support combustion but does not generate heat on its own; rather, it increases the intensity of a fire if one is present. Therefore, the coffeemaker stands out as a clear example of an appliance that can produce heat sufficient to ignite flammable materials.