In the Hoop’s process for refining of aluminum, the fused materials form three different layers and they remain separated during electrolysis also. This is because

• A

  There is special arrangement in the cell to keep the layers separate
• Correct answer
  B

  The three layers have different densities
• C

  The three layers are maintained at different temperatures.
• D

  The upper layer is kept attracted by the cathode and the lower layer is kept attracted by the anode.

Hence, the correct answer is option: 'B'.