Which property allows certain materials to attract iron objects?

Magnetism is the property that enables certain materials to attract iron objects. This phenomenon occurs due to the alignment of magnetic domains within ferromagnetic materials, such as iron, nickel, and cobalt. When these materials are magnetized, they produce a magnetic field, which can exert a force on other magnetic materials or ferromagnetic objects nearby.

In the context of attraction, materials that are magnets have the ability to interact with ferrous materials, resulting in an attractive force. This is a fundamental property of magnetism and is crucial in many applications, such as electric motors, generators, and magnetic storage devices.

The other options do not relate to the attraction of iron objects in this context. Conductivity pertains to a material’s ability to carry electric current, resistance describes a material's opposition to the flow of electric current, and capacitance relates to a material’s ability to store electric charge. These properties are significant in electronics and electrical engineering but are not responsible for the magnetic attraction observed with iron objects.