Which of the Following is the Smallest Closed System

Question

Which of the following is the smallest closed system?
A)a cell
B)an organism
C)an ecosystem
D)Earth
E)the universe

Accepted Answer

The universe is the smallest closed system because it encompasses all matter, energy, and space, with no energy or matter entering or leaving it. All other options are part of the universe and not closed systems on their own, as they exchange energy or matter with their surroundings.