To prevent rusting, iron sheets are commonly protected by applying a layer of which metal?

1. Rusting is the corrosion of iron in the presence of air and water. 2. To prevent it, a protective layer of a more reactive metal, zinc, is applied on the iron sheets. 3. Copper is less reactive than iron and would not protect it the same way. 4. Silver is costly and unreactive for this purpose, and sodium is far too reactive to use as a coating, so those options are wrong. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 3 "Chemical Reactions and Equations", p.54_