D.) Options A and B
For an ionic bond to form between two atoms:
A.) The atoms must have an electronegativity difference of at least 1.7. Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. When the electronegativity difference between two atoms is large (typically 1.7 or greater), it indicates that one atom has a much stronger attraction for electrons, leading to the formation of an ionic bond.
B.) They involve a transfer of electrons from a metal to the nonmetal. In an ionic bond, one atom (usually a metal) donates electrons to another atom (usually a nonmetal) to achieve a more stable electron configuration. This transfer of electrons results in the formation of positively charged ions (cation) and negatively charged ions (anion), which are attracted to each other and form the ionic bond.