A sacrificial anode is made of a material that is more easily oxidized than the protected metal. Which option matches this description?

• A. A noble metal coating
• B. A polymer layer
• C. A material that is more easily oxidized than the protected metal
• D. A protective passive layer

Answer: (C)

The idea being tested is sacrificial protection: you protect a metal by using a partner material that is more easily oxidized. When the two metals are connected, the more reactive one acts as the anode and corrodes first, donating electrons to the protected metal. This keeps the protected metal’s surface cathodic and resistant to oxidation, so the sacrificial material sacrifices itself while the protected metal stays safe. This is why the option describing a material that is more easily oxidized than the protected metal is the correct match. Other methods like a noble metal coating, a polymer barrier, or a passive protective layer slow or block corrosion in different ways, but they do not rely on one metal preferentially oxidizing to protect the other.