A closed system is a system that makes no physical or chemical exchanges with its environment. Of these systems provided as choices (tree, human, clock, car), only a clock does not make exchanges with the environment, except for energy.
Therefore, of that list, only a clock would be a closed system.
Hope that helped! =)
I’m not sure that your choices are because it says select all that apply but I would tell the mother to stop giving the baby cows milk. The baby needs more iron which is in breast milk or formula if not she can become anemic and cows milk is not easy to digest for babies.
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I am totally interested in good classic rock music and fast cars n i love nascar
