In order to prevent an iron object from rusting, the object is often connected to another metal that can offer cathodic protection. What would be a good metal?

A good metal for providing cathodic protection to prevent rusting of an iron object is a metal that is more electrically active or reactive than iron. By connecting a more active metal to the iron object, it will act as a sacrificial anode and will corrode instead of the iron. This process, known as galvanic or sacrificial corrosion, helps protect the iron from rusting. The most commonly used metal for cathodic protection is zinc, although other metals such as aluminum and magnesium can also be effective.