Considering Ellingham diagram, which of the following metals can be used to reduce alumina (${\text{Al}}_2{\text{O}}_3$)?

In the Ellingham diagram, a metal can reduce the oxide of another metal if its line (Gibbs free energy of formation of oxide) lies below the line of the other metal's oxide at a given temperature. Below approximately $1350^{\circ }\text{C}$, the line for $\text{Mg}\to \text{MgO}$ lies below the line for $\text{Al}\to {\text{Al}}_2{\text{O}}_3$, meaning $\text{Mg}$ can reduce alumina in that temperature range.