The correct answer is B. Zinc.
A dry cell is a type of battery that uses a chemical reaction to generate electricity. The anode in a dry cell is made of zinc, which is a metal that is easily oxidized. When the battery is in use, the zinc anode reacts with the electrolyte to produce electrons. These electrons flow through the circuit, providing power to the device that is being powered by the battery.
The other options are incorrect because they are not metals that are easily oxidized. Copper, cadmium, and graphite are all metals that are resistant to oxidation. This means that they would not be able to react with the electrolyte in a dry cell to produce electrons.
In addition, copper is a conductor of electricity, while cadmium and graphite are not. This means that they would not be able to carry the current that is produced by the chemical reaction in a dry cell.
Therefore, the only option that is correct is B. Zinc.