Best way to prevent rusting of iron is by

making iron cathode.

The best way to prevent rusting of iron is by making iron the cathode in an electrochemical cell.

Rusting is an electrochemical process that occurs when iron reacts with oxygen and water in the presence of an electrolyte (such as saline water). In this process, iron acts as the anode, where oxidation occurs, resulting in the formation of iron(II) ions and releasing electrons. These electrons then combine with oxygen and water at another location on the iron surface to form hydroxide ions, which further react with iron(II) ions to form rust.

By making iron the cathode, we can prevent the oxidation of iron and the subsequent rusting. When iron is made the cathode in an electrochemical cell, it becomes the site for reduction reactions instead of oxidation. This can be achieved through various methods such as coating the iron with a protective layer, using sacrificial anodes, or applying a cathodic protection system.

Therefore, the correct answer is (1) making iron the cathode.