* Ductility refers to a material's ability to be drawn into thin wires without breaking. This is closely related to a material's ability to deform under tensile stress.

* Iron (Fe) is a metal. Metals have a characteristic metallic bonding structure where electrons are delocalized, allowing them to slide past each other. This makes them highly ductile.

Let's look at the other options:

* Carbon (C) exists in various forms, but generally, it's brittle. Diamond, a form of carbon, is extremely hard but not ductile. Graphite is more ductile but still not as much as metals.

* Silicon dioxide (SiO2), commonly known as silica, is a ceramic material. Ceramics are generally brittle and lack the ability to deform significantly.

* Sodium chloride (NaCl), table salt, is an ionic compound. Ionic compounds are brittle because the strong electrostatic forces between ions make it difficult to deform the structure without breaking the bonds.

In summary: Ductility is a characteristic of metals, and iron is a highly ductile metal.