Which of the following is not correctly matched with respect to the processes involved in the extractive metallurgy of the respective metal ?
A. `Al_2O_3. 2H_2OtoAl` : Leaching, precipitation , calcination and electrolytic reduction (molten state)
B. `Ag_2StoAg` Leaching and displacement method
C. `PbS to Pb` Froth flotation process , roasting and self reduction
D. `KCl. MgCl_2. 6H_2OtoMg` Dehydration by simple heating and electrolytic reduction in aqueous phase.