What material is most commonly used as a sacrificial anode for the purposes of minimizing the galvanic corrosion of steel and cast iron?

Correct Answer: Option C — Zinc

Zinc is the most common sacrificial anode material because it is more electronegative than steel or cast iron. In a galvanic cell, the zinc corrodes preferentially, protecting the structural metal from oxidation. This is standard practice for protecting ship hulls, heat exchanger water boxes, and piping systems.