Concept:Rust is the reddish-brown substance formed when iron corrodes in the presence of oxygen and moisture.Explanation:Iron reacts with oxygen and water over time to form rust.The main component of rust is hydrated iron(III) oxide, often written in simplified form as Fe2O3.This formula shows that each unit contains two iron atoms and three oxygen atoms.Fe3O4 is magnetite, FeO is iron(II) oxide, and Fe(OH)3 is iron(III) hydroxide.Among the options, the correct representation of rust is Fe2O3.Answer:D. Fe2O3