The correct answer is C) Zinc. Zinc is the most commonly used material for sacrificial anodes to minimize galvanic corrosion of steel and cast iron. Zinc is more electrochemically active than steel or cast iron, meaning it will preferentially corrode and protect the more noble metal surfaces. This is in accordance with the galvanic series, which ranks metals based on their tendency to corrode. Steel and cast iron are higher on the series, making zinc a suitable sacrificial anode material. The other options are incorrect because bronze and brass contain copper, which is less active than steel and cast iron, making them unsuitable as sacrificial anodes. Platinum is a noble metal, meaning it is less susceptible to corrosion, and would not provide the necessary galvanic protection.