When `K_(2)Cr_(2)O_(7)` is heated with conc. `H_(2)SO_(4)` and soluble chloride such as KCl :
A. red vapours of `CrO_(2)Cl_(2)` are evolved
B. `Cl^(-)` ion is oxidized to `Cl_(2)` gas
C. `CrCl_(3)` is formed
D. `Cr_(2)O_(7)^(2-)` ion is reduced to green `Cr^(3+)` ion