The correct option is B The ore is grounded, extracted with hot 20% MgCl2 solution, filtered off and crystallized
Carnalite is always found mixed with NaCl and MgO4. The ore is grounded and extracted with hot 20% MgCl2 solution. Carnalite dissolves whereas NaCl and MgO4 remains undissolved. These are filtered off and the solution (which contains only carnalite) is crystallized so that KCl (cubic crystals) separates. MgCl2 remains in the solution.