Which item found at a fire scene could suggest the involvement of a plant?

The indication of a plant's involvement at a fire scene is best suggested by the presence of excelsior. Excelsior is a form of wood shavings or fibers that are often used for packing or as cushioning material. Its organic composition and flammable nature can support combustion, distinguishing it from the other materials listed.

While matches, gasoline, and cotton may also be related to fire behavior, they do not inherently indicate the presence or involvement of plant material in the same way excelsior does. Matches are simply igniting tools, gasoline is a petroleum by-product, and cotton, although derived from a plant, does not suggest the broader context of organic materials more characteristic of a natural fire environment like excelsior does. Understanding these nuances is crucial when investigating fire scenes and drawing conclusions about potential fuel sources.