Answer:
D. aluminum.
Explanation:
Conductive materials refer to those materials which have lower resistance to the movement of electric charges, the higher this resistance, higher the conductivity, because electrons would move faster.
Think about friction, conductive materials have low friction for electrons to move, that's why the can easily conduct electricity, like metals.
Now, among the options, aluminum is a metal, which means it can easily conduct electric currents, thanks to its internal structure, electrons can travel faster than inside wood, cork or soil.
Therefore, the right answer is D. aluminum.