The best answer is D.
Carbon has an affinity for bonding with other small atoms including other carbon atoms, via the formation of stable covalent bonds.
In spite of the fact that carbon is present in a vast number of compounds, carbon is weakly reactive compared to other elements.
It has the ability to form very long chains of strong and stable interconnecting C-C bonds. This property allows carbon to form an almost infinite number of compounds. There are more known carbon-containing compounds than all the compounds of the other chemical elements combined except those of hydrogen because almost all organic compounds contain hydrogen as well.
