What must a material have to be considered for fire ignition?

For a material to be considered for fire ignition, it is essential that it is situated close enough to an ignition source to receive sufficient energy to initiate combustion. Proximity to the ignition source is critical because even the most flammable materials will not ignite if they are too far from the heat or flame that can raise their temperature to the point of combustion. This principle highlights the significance of both the characteristics of the material and its environmental context in the ignition process.

The other choices, while relating to properties of materials, do not solely define the conditions for ignition. Flammability is important, but without the necessary heat from an ignition source, a flammable material will not ignite. Materials with a high flash point can resist ignition at high temperatures; therefore, they may not catch fire easily, and thus proximity to the ignition source becomes crucial. Similarly, materials treated with fire retardants are designed to prevent ignition and delay combustion, which diminishes their ability to ignite irrespective of their proximity to an ignition source.