Which of the following represents the Etard reaction?

• A
  $C_6H_5CH_3 + 2CrO_2Cl_2$ $\rightarrow C_6H_5CH(OCrOHCl_2)_2$ $\xrightarrow{H_3O^{+}} C_6H_5CHO$
• B
  Toluene reacting with $CrO_2Cl_2$ in $CS_2$ followed by hydrolysis to form benzaldehyde.
• C
  Toluene reacting with $CrO_3$ and acetic anhydride followed by hydrolysis to form benzaldehyde.
• D
  Gattermann-Koch reaction of toluene with $CO$ and $HCl$ in the presence of anhydrous $AlCl_3$.