What is the most likely reason that nonmetals are electrical insulators?

Question

Since valence shells are mostly empty in nonmetal atoms, the atoms attract and hold any electrons they can in order to fill their valence shells.
Since valence shells in nonmetal atoms are almost full, the atoms attract electrons and hold them tightly to fill their valence shells.
Since all nonmetals have valence shells that are full, they hold electrons tightly to avoid changing.
Since all nonmetals have valence shells that are completely empty, they do not attract or release any electrons.

Answer 1

The most likely reason that nonmetals are electrical insulators is because their valence shells are almost full. Nonmetal atoms attract electrons and hold them tightly to fill their valence shells, making it difficult for electrons to move freely and conduct electricity.