What property of metals allows them to be malleable?

The ability of metals to be malleable is primarily due to the characteristic structure of metallic bonding. In metallic bonds, atoms are arranged in layers, which are held together by a 'sea of delocalized electrons' that move freely around the positively charged metal ions. When pressure is applied to a metal, the layers of atoms can slide over one another without breaking the metallic bond. This sliding motion is what allows metals to be shaped into thin sheets or other forms without fracturing.

The options regarding strong ionic bonds, simple molecular structures, and the presence of covalent bonds do not accurately explain the malleability of metals. Ionic bonds are typically strong but involve rigid lattices that do not allow movement, while simple molecular structures lack the necessary atomic arrangement for malleability. Covalent bonds are strong but generally form rigid structures that do not exhibit malleability like metals do. Hence, the correct understanding of metallic bonding is fundamental to grasping why metals possess this malleable property.