Concept:Chemical bonding by complete electron transfer from one atom to another creates ions.Explanation:In ionic bonding, a metal atom loses electrons to become a positively charged cation.A non-metal atom gains those electrons to become a negatively charged anion.The oppositely charged ions are then held together by strong electrostatic forces of attraction.This transfer of electrons is the key feature that distinguishes ionic bonding from other bond types.Answer:A. Ionic bonding