Which of the following is considered a non-biological evidence type in a crime scene investigation?

In a crime scene investigation, non-biological evidence refers to items that do not originate from a living organism. The correct choice, which is the gun, fits this category because it is an inanimate object made of metal and other synthetic materials, representing a mechanical or physical piece of evidence rather than something that comes from a biological source.

On the other hand, hairs, fingerprints, and fabric all contain or may originate from biological sources. Hairs can come from humans or animals, fingerprints consist of the unique patterns left by the friction ridges of human skin, and fabric can often be derived from clothing that may have been worn by a person, which can trace back to biological origin. This differentiation is crucial in crime scene investigations, as it assists in analyzing and categorizing the evidence collected to determine its relevance to the case.