Question

open and closed systems
why are closed systems considered theoretical models?
they are systems that are not fully understood by environmental scientists.
they are very common to see in nature and most ecosystems are examples.
closed systems dont exchange anything with their surroundings and rarely occur.

Explanation:

The text states that closed systems are isolated, self - contained, and lack interactions with other systems. They don't exchange energy, matter, or information with their surroundings and rarely occur naturally. This matches the third option which mentions no exchange with surroundings and rare occurrence.

Answer:

Closed systems don't exchange anything with their surroundings and rarely occur.