题目选项分析

Extracting pure aluminum from bauxite and other ores by means of the Hall-Héroult process, in which a vast amount of electrical energy separates the element from aluminum oxide, makes aluminum an energy-dense resource with a huge carbon footprint.

Extracting pure aluminum from bauxite and other ores by means of using the Hall-Héroult process, in which a vast amount of electrical energy separates the element from aluminum oxide, is making aluminum an energy-dense resource with a huge carbon footprint.