During the metallurgy of aluminium,bauxite is dissolved in cryolite $(Na_3AlF_6)$ because:

Upon heating with $Cu_2S$,the reagent$(s)$ that give copper metal is/are:
$(A)$ $CuFeS_2$
$(B)$ $CuO$
$(C)$ $Cu_2O$
$(D)$ $CuSO_4$

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The reduction of a metal oxide is easier if the metal formed is in liquid state than solid state.
Reason $R$: The value of $\Delta G^{\ominus}$ becomes more on negative side as entropy is higher in liquid state than solid state.
In the light of the above statements,choose the most appropriate answer from the options given below.

The flux used to remove the $FeO$ impurity present in the mixture obtained from the roasting of copper pyrites,and its nature,is .....

In metallurgy,aluminum acts as a .....

Which process is used for the extraction of copper from low-grade copper ores?