What distinguishes "touch DNA" from other forms of DNA?

"Touch DNA" is distinguished by its collection method, specifically from contact with surfaces. This type of DNA is obtained when a person touches or comes into contact with an object or surface, leaving behind skin cells that carry their unique genetic information. This is particularly useful in forensic science for identifying individuals who may have touched a particular item at a crime scene.

The other options do not accurately describe "touch DNA." For instance, it is not limited to bodily fluids, which would include other forms of DNA like blood or saliva. Additionally, "touch DNA" is not specifically linked to dirt collection, as it focuses on the genetic material left behind from a person's skin. Lastly, while DNA can degrade over time, "touch DNA" itself does not require high levels of degradation; rather, it can often still be useful even with minimal degradation, which distinguishes it further from other forensic techniques that may rely on larger or more intact samples.