What does galvanic corrosion protect when two dissimilar metals are combined?

When two dissimilar metals are combined, galvanic corrosion occurs due to the electrochemical reaction between them. In this context, the less active metal, often referred to as the cathode, is protected from corrosion. This happens because the more active metal, known as the anode, tends to corrode preferentially.

The principle behind this protection lies in the reactivity of the metals involved. The more active metal, which is more prone to oxidation, will dissolve and lose material to the environment while shielding the less active metal from corroding. The less active metal, therefore, retains its integrity and is protected from corrosion over time.

This is why the correct answer indicates that the less active metal is the one being protected in a galvanic couple. The other options do not account for the fundamental principle of galvanic corrosion, which highlights this protective action towards the less active, or more noble, metal in the pair.