Fuel elements in models are primarily grouped based on which of the following characteristics?

Fuel elements in models are primarily grouped based on species, fuel form, size, and arrangement because these characteristics directly influence how the materials will burn and interact in a fire scenario. Species refers to the type of material, such as hardwood or softwood, which affects its combustion properties. Fuel form describes the physical state of the fuel, like logs versus chips, which impacts the surface area available for burning. Size and arrangement refer to how the fuel is organized and how the different pieces occupy space, affecting airflow and heat transfer during combustion.

Understanding these aspects is essential in fire investigation, as they help determine the fire's behavior, intensity, and spread. By analyzing these characteristics, investigators can better understand the conditions under which a fire occurred and the factors that contributed to its development. This knowledge is crucial for drawing accurate conclusions about fire origin and cause.