The correct option is A A.→p;B.→q;C.→p,r;D.→p,s.
PbS⟶PbO
This is an example of a sulphide ore getting converted only to an oxide ore.
Hence, it is actually roasting!
CaCO3⟶CaO
Likewise, this is a carbonate ore getting calcined to an oxide ore! Calcination!
ZnS⟶Zn
The above is actually a sulphide ore getting converted into metal!
From the given options, well need "roasting" to convert it to an oxide, which could then
be reduced to the metal using carbon reduction. Zn is way too active a metal for self-reduction!
For extraction of copper, partial roasting of the sulphide ore followed by self-reduction is the way to go!
Cu2S⟶Cu