Answer: A. an ionic bond.
Explanation:
An ionic bond is formed when an element completely transfers its valence electron to another element. The element which donates the electron is known as electropositive element and forms cation and the element which accepts the electrons is known as electronegative element and forms the anion.The cations and anions being oppositely charged attract each other through strong coloumbic forces and form an ionic bond.
A covalent bond is formed when an element shares its valence electron with another element. This bond is formed between two non metals.
A polar covalent bond is defined as the bond which is formed when there is a difference of electronegativities between the atoms.
A non-polar covalent bond is defined as the bond which is formed when there is no difference of electronegativities between the atoms.
