Which statement best explains why carbon is present in so many kinds of molecules? (points : 1)
it is rare on earth.

it can form four covalent bonds.

it has no valence electrons.

it can become an ion

The statement which best explains why carbon is present in so many kinds of molecules is because it can form four covalent bonds.
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.