Which of the following process is used in the extractive metallurgy of magnesium ?

Given Data: It is asked in question that from the given option which process is used in the extractive metallurgy of magnesium.

Concept Used: Techniques for refining metals

Detailed Solution:

We know that Highly electropositive metals (eg.,Alkali and alkaline earth metals and $\mathrm{Al}$ ) are extracted by the electrolysis of their fused salts.

Therefore, Magnesium is extracted by the electrolysis of fused $\mathrm{MgO}$ (anhydrous magnesium chloride) obtained from carnallite and magnesite.

Magnesium is obtained at the cathode. 

Cathode: ${\mathrm{Mg}}^{2+}+2\mathrm{e}⟶\mathrm{Mg}$

Anode: $2{\mathrm{Cl}}^{-}⟶{\mathrm{Cl}}_2+2\mathrm{e}$

Hence, option(A) is the correct answer.