An aqueous solution of metal ion `M_1` reacts separately with reagents `Q and R` in excess to give tetrahedral and square planar complexes, respectively. An aqueous solution of another metal ion `M_2` always forms tetrahedral complexes with these reagents. Aqueous solution of `M_2` on reaction with reagent S gives white precipitate which dissolves in excess of S. The reactions are summarized in the scheme given below :
`M1, Q and R`, respectively are :

Options

A. `Zn^(2+)`, KCN and HCl
B. `Ni^(2+)`, HCl and KCN
C. `Cd^(2+)`, KCN and HCl
D. KOH