Answer:
Stem cells are currently being used to replace damaged cells or to treat some forms of cancer, usually taken from the adult hip (bone marrow)
The statement which best explains why carbon is present in so many kinds of molecules is because <u>it can form four covalent bonds.
<em /></u>It isn't rare on Earth, so A is incorrect. It has valence electrons, so C is incorrect. It cannot become an ion, so D is incorrect.<u>
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I would have to say conspiracy.
