An inorganic salt when heated with concentrated `H_(2)SO_(4)` evolves a colourless pungent smelling gas but with concentrated `H_(2)SO_(4) " and" MnO_(2)`, evolves a cxoloured pungent smelling gas which bleaches moist litmus paper. The coloured gas is :
A. `NO_(2)`
B. `Cl_(2)`
C. `Br_(2)`
D. `l_(2)`