The correct answer is C. Zinc.
Galvanized iron sheets are made by coating iron or steel with a thin layer of zinc. This coating protects the iron or steel from rust and corrosion. Zinc is a very effective corrosion inhibitor, and it forms a strong bond with iron or steel. This makes galvanized iron sheets very durable and long-lasting.
Lead, chromium, and tin are also metals that can be used to coat iron or steel. However, they are not as effective as zinc at preventing corrosion. Lead is a soft metal that is easily corroded. Chromium is a hard metal that is resistant to corrosion, but it is also expensive. Tin is a soft metal that is easily corroded, and it does not form a strong bond with iron or steel.
Therefore, the best metal to use to coat iron or steel is zinc. Zinc is a very effective corrosion inhibitor, it forms a strong bond with iron or steel, and it is relatively inexpensive.