When a metal rod M is dipped into an aqueous colourless concentrated solution of compound N, the solution turns light blue. Addition of aqueous `NaCl` to the blue solution gives a white precipitate O. Addition of aqueous `NH_(3)` dissolves O and gives an intense blue solution.
The compound N is
A. `AgNO_(3)`
B. `Zn(NO_(3))_(2)`
C. `Al(NO_(3))_(2)`
D. `Pb(NO_(3))_(2)`
