Which characteristics are common to amphibians, lemurs, and humans?

vertebrae, tetrapod, hair
amniotic egg, hair, biped
tetrapod, vertebrae
tetrapod, hair

Let's see what these words mean:

Vertebrae means a backbone as well as an internal skeleton

Hair is the body's way of creating a defense for the skin (and additionally to look bigger)

Tetrapod is a four footed animal

Amniotic egg means that the embryo develops inside an egg.

Biped means using two feet to walk.

Amphibians, lemurs, and humans both have vertebrae and tetrapod. While humans do not walk on four legs it is said that humans are classified as that group

some think that theories become laws, but theories and laws have separate and distinct roles in the scientific method. a law is a description of an observed phenomenon in the natural world that hold true every time it is tested. it doesn't explain why something is true; it just states that it is true.