Question

in the real world, are there any closed systems on earth?
no, none of the systems on earth are closed.
yes, all natural systems are closed.
yes, all ecosystems are closed systems.

Explanation:

A closed system is one that does not exchange matter with its surroundings, though it can exchange energy. On Earth, all systems (including ecosystems and natural systems) exchange matter with the rest of the universe (e.g., Earth's atmosphere interacts with space, organisms take in and release matter). So no systems on Earth are truly closed. The first option correctly reflects this. The second is wrong as natural systems do exchange matter, and the third is wrong as ecosystems exchange matter (e.g., nutrient cycles involve exchanges with the environment beyond the ecosystem's strict boundaries).

Answer:

A. No, none of the systems on Earth are closed.