What takes place when zinc metal is added to an aqueous solution containing magnesium nitrate and silver nitrate?
(P). Zn is oxidized
(Q). `Mg^(2+)` is reduced.
(R). `Ag^(+)` is reduced.
(S). No reaction takes place.
A. P and Q only
B. P and R only
C. P,Q and R only
D. S only