Ionic bonding would be the answer because they transfer electrons. This gives them a charge. If it loses electrons, it becomes an cation, with a positive charge. While if they gain an electron, they get a negative charge, and become a anion. Transferring an electron is losing or gaining, therefore your answer would be that since electrons are permanently being transferred, the answer is IONIC BOND.
Covalent bonds is a wrong answer because they share electrons, which gives them no charge (neutral).
Also, metallic bonding is not the correct answer.
So our final answer: A- Ionic bond
