Which of the following method can be used to prevent rusting of iron?

All of these

The correct answer is option 4. All of these.

Iron gets corroded called rusting of iron.

The process of rusting can be represented by the following equation:

Iron (Fe) + Oxygen (O₂, from the air) + water (H₂O) → Rust (iron oxide Fe₂O₃)

Prevention from rusting of iron:

One simple way is to apply a coat of paint or grease. In fact, these coats should be applied regularly to prevent rusting.

Another way is to deposit a layer of a metal like chromium or zinc on iron.