A white crystalline substance dissolves in water. On passing `H_2 S` in this solution, a black ppt. is obtained. The black ppt. dissolves completely in hot `HNO_3`. On adding few drops of conc. `H_2 SO_4`, a white ppt. is obtained. The ppt. is that of
A. `BaSO_(4)`
B. `SrSO_(4)`
C. `PbSO_(4)`
D. `CdSO_(4)`