The text states that every external structure has a specific "function." What is the best definition of a structure's function?

The material the structure is made of

The specific job it performs for survival

The way the structure changes over the animal's lifetime

The overall size and weight of the body part compared to the rest of the animal

A snake flicks its tongue in the air to "taste" chemical particles, which helps it track prey. This behavior shows how an external structure...

is used to build a nest or shelter for its young to keep them safe.

can be used to gather sensory information that helps the animal find food.

changes color to warn other animals that it is dangerous and should be avoided.

is used primarily for communicating with other snakes over long distances.

They are used primarily to attract mates.

They make the animal look more appealing.

They help the animal find shelter from rain.

They gather critical information from the environment, allowing the animal to find food and avoid danger.