Correct Answer - D
Zinc is commonly used for covering iron surfaces. The process of covering iron with zinc is called galvanisation. If some scratches occur on the protective zinc film on coated iron, even then iron will not be rusted. This is due to the fact that because of scrathces, both zinc and iron gets exposed to oxidation to iron, because the reduction potential of zinc is less than the reduction potential of iron. So, zinc coating is the best and durable method for protecting of iron.
