Answer:
c. pairs of electrons are shared between two nonmetal atoms
Explanation:
Bonding between elements solely depends on their electronegativity. When there is large difference in electronegativity, those atoms form ionic bonds. Covalent bonds form when the difference is minimal, or none at all. When the difference between electronegativities is 0 or very close to 0, then they form pure covalent bonds, or nonpolar bonds. An example of this are diatomic molecules. Diatomic molecules are two of the same atom that form nonpolar covalent bonds because their electronegativy difference is 0, as they have the same electronegativity. When the electronnegativties have bit of difference, they form polar covalent bonds.