Magnesium is extracted electrolysing fused magnesium chloride containing `NaC1`and `CaC1_(2)`using:
A. a nickel cathode and a graphite anode.
B. the iron container as anode and a nickel cathode.
C. the iron container as cathode and a graphite rod as anode.
D. the nickel container as cathode and iron as anode.
