Which one of the following metal oxides CANNOT be reduced to the metal by heating with carbon?

1. Carbon reduces oxides of moderately reactive metals (Pb, Zn, Fe) at high temperature. 2. Aluminium is highly reactive; $Al_2O_3$ is far more stable than $CO/CO_2$, so carbon cannot reduce it. 3. Aluminium is therefore extracted by electrolysis, not carbon reduction. _Source: Samacheer Kalvi Class 12 Chemistry Vol.1, Unit 1 'Metallurgy', §1.3.2 / Evaluation Q.4_