What is a zoonotic disease?

• A. A disease that can be transmitted from one laboratory animal to another
• B. A disease that can be transmitted from one human to another
• C. A disease that can be transmitted from an airborne particle to an animal
• D. A disease that can be transmitted from animals to humans or vice versa

Answer: (D)

Zoonotic disease refers to a disease that can be transmitted between animals and humans, in either direction. This includes animal-to-human transmission and human-to-animal transmission. The best answer captures that cross-species potential. The other options are too limited: they describe transmission within one species or a single route that doesn’t involve both humans and animals.