I believe the answer is b
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The answer is D.rainforest. it is a very complex ecosystem with variety of plants and animals.
Two substances in the body that will move based on the principle of diffusion are CARBON DIOXIDE AND OXYGEN.
Diffusion is the process by which molecules of a substance move from the region of higher concentration to the region of lower concentration. Carbon dioxide and oxygen can easily move in an out of the cell via diffusion.<span />