The dorsal horns are the thinner projections of dark matter that jut out from the rest towards the dorsal / back side of the spinal cord. the ventral horns are the wider projections of dark matter towards the ventral / front side of the spinal cord.
I think the correct answer from the choices listed above is option A. Cells divide in order to maintain a surface area large enough to support their cytoplasm. When they divide, their volume decreases which enables them to obtain enough nutrient and expel wastes.
Answer: "chemoautotrophs" .
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Reason is humans have not yet completed demographic transition