Choose all that explain why carbon is so important to life.

Carbon (C) appears in the second row of the periodic table and has four bonding electrons in its valence shell.
Carbon can form ionic bonds when combining with metals and covalent bonds with nonmetals.
Carbon can bond to itself in many different ways: chains, rings, branched chains.
Hydrocarbons contain only carbon, hydrogen, and oxygen.
Carbon can form single, double or triple covalent bonds.
Because carbon can bond in so many different ways, a single molecule can have different bonding configurations or isomers.