Three separate samples of a solution of a single salt gave these results. One formed a white ppt. with excess ammonia solution, one formed a white ppt. with dil. NaCl solution and one formed a black ppt. with `H_(2)S` . The salt could be
A. `AgNO_(3)`
B. `Pb(NO_(3))_(2)`
C. `Hg(NO_(3))_(2)`
D. `MnSO_(4)`