In the given reactions identify the reagent $$A$$ and reagent $$B$$

A

$$A - CrO_3$$, $$B - CrO_3$$

B

$$A - CrO_3$$, $$B - CrO_2Cl_2$$

C

$$A - CrO_2Cl_2$$, $$B - CrO_2Cl_2$$

D

$$A - CrO_2Cl_2$$, $$B - CrO_3$$