Concept:Rusting of iron requires both moisture and oxygen.
So, rust can be prevented by stopping iron from coming into contact with either.
Explanation:Rusting is the reaction of iron with oxygen and water to form hydrated iron(III) oxide,
Fe2O3⋅xH2O.
Painting gives a protective coating that blocks air and moisture from reaching the iron surface.
Alloying, such as mixing iron with chromium to make stainless steel, makes the metal resistant to rust.
Keeping iron in a desiccator removes the moisture from the surrounding air, so rusting cannot occur.
Keeping iron in a moist environment supplies water, which actually encourages rusting rather than preventing it.
Thus, the methods that prevent rusting are painting, alloying, and keeping iron in a desiccator, that is, I, II, and III.
Answer:C. I, II and III only