Scenario: A bloody sweatshirt is recovered from a crime scene and is believed to belong to the perpetrator.

Question: Which of the following can be a source of the perpetrator's DNA evidence from the sweatshirt? (Mark all that apply)

A. Blood
B. Gunpowder residue
C. Saliva that dripped or rubbed onto the shirt
D. Chest or other body hairs found on the shirt
E. Skin cells that rubbed onto the shirt

Perpetrator's DNA evidence on a sweatshirt can come from blood, saliva, body hairs with roots, and skin cells, but not from gunpowder residue. Thus Option b is Correct.

Sources of the perpetrator's DNA evidence from the sweatshirt include: A. Blood, which can yield a complete DNA profile; C. Saliva that dripped or rubbed onto the shirt, as it often contains epithelial cells; D. Chest or other body hairs found on the shirt, specifically those with the root attached, which can be a source of nuclear DNA; and E. Skin cells that have rubbed onto the shirt, through the process of shedding known as 'touch DNA' or 'contact DNA.'

Gunpowder residue (B) doesn't contain DNA and therefore is not a source of DNA evidence. However, all biological sources mentioned can carry the unique genetic marker of the individual, helping to link the evidence to a specific person. Thus Option b is Correct.