What keeps an ionic bond held together?

a) gravity

b) the sharing of electrons

c) energy of valence electrons

d) attraction between oppositely-charged ions

D) Attraction between oppositely-charged ions.

In ionic bonds, one atom is negatively charged, and one atom is positively charged. The positively charged atom gives its electrons, and the negatively charged atom receives the electrons--thus, the opposite charge attracts them to one another and holds them together. That simple.

Answer: D) Attraction between oppositely-charged ions