Which of the following is NOT a reason for carbon's versatility?

The formation of ionic bonds is not a reason for carbon's versatility; carbon almost exclusively forms covalent bonds by sharing electrons due to its small size and energy considerations. Carbon has the unique ability to form long chains and rings by bonding with other carbon atoms, a property known as catenation, which leads to a massive variety of molecules. With four valence electrons, carbon is tetravalent, meaning it can bond with four other atoms, allowing for complex branching and 3D structures.