According to Ellingham Diagram, the Reduction of Al₂O₃ with Carbon $\degree$

According to Ellingham diagram, the reduction of Al₂O₃ with carbon is feasible above 2400 $\degree$ C, why is Al₂O₃ reduced in practice electrochemically rather than chemically with carbon?

A) The temperature is too high and maintaining it is too expensive.
B) It is difficult to achieve correct Al₂O₃-to-carbon ratio in practice.
C) Formed Al is reducing enough to reduce CO and CO₂ back to carbon.