(a) Roasting and calcination are the two processes to reduce the metal oxides to the respective metals.
(b) Magnesium is extracted from its ore by electrolytic reduction process.
(c) Cryolite is used in metallurgy of aluminium in order to increase the fusibility and conductivity
(d) I Hall's process bauxite is leached with the help of Na2CO3.
Which of the following options regarding the above statements is correct?