Calcium is extracted by the electrolysis of

The chemical composition of the slag formed during the extraction of $Cu$ from copper pyrites is ......

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A):$ Aluminium is extracted from bauxite by the electrolysis of a molten mixture of $Al_2O_3$ with cryolite.
Reason $(R):$ The oxidation state of $Al$ in cryolite is $+3$.
In the light of the above statements,choose the most appropriate answer from the options given below:

Explain the use of physico-chemical principles in metallurgy.

The chemical that is added to reduce the melting point of the reaction mixture during the extraction of aluminium is

Heating a mixture of $Cu_2O$ and $Cu_2S$ gives: