<span>A. Primary Succession is my answer! :)
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Skin is covered by epithelial cells. Liver is mainly made up of hepatocytes though fibrous and fatty tissues are also present.<span>Cells of skin epithelium are present in different layers. Lower most layer on basement membrane (all epithelia possess this barrier on which epithelial cells grow) are newly generated. These cells gradually acquire a protective protein keratin but loses vitality. Thus by the time cells reach top most layer of skin they are all dead cells.</span>
This is referred to as allopatric speciation where species are separated geographically and evolve into two different species over time
It is Nucleic Acids, they consist of long chains of units like the proteins, but still both are different.
