Which description matches the term in vitro?

• A. Testing inside a living organism
• B. A study of tissue movement in vivo
• C. A clinical trial in humans
• D. Testing performed outside a living organism, typically in a lab environment

Answer: (D)

In vitro means testing outside a living organism, typically in a lab environment where conditions are controlled, such as in petri dishes, test tubes, or cell cultures. This allows researchers to study specific variables without the complexity of a whole organism.

So the description that fits is testing performed outside a living organism, typically in a lab environment. This contrasts with experiments conducted inside a living organism (in vivo), like clinical trials in humans or studies of tissue movement within an organism.