Answer: C) Non-metals can share pairs of electrons and form covalent bonds
Explanation: The principal reason why it is non-metals that can form covalent bonds is because of their electronegativities. Electronegativity is the tendency of an atom to attract electrons towards itself.
The participating atoms in a covalent bond have to be able to hold the shared electron in place & it is this attraction towards the centre of each participating atom that holds the electrons in place. Metals aren't electronegative, they don't attract electrons towards each other, they'd rather even push the electrons away from themselves (electropositive) to be stable. The closest concept of metals to shared electrons is in metallic bonding, where metals push and donate their valence electrons to an electron cloud which is free to move around the bulk of the metallic structure. But this is nowhere near the type of bonding that exist in covalent bonds.