A solution containing 2.675 grams of ${\text{CoCl}}_{\text{3}}{\text{\hspace{0.17em}.\hspace{0.17em}6NH}}_{\text{3}}$ (molar mass = ${\text{267.6\hspace{0.17em}gr\hspace{0.17em}.\hspace{0.17em}mole}}^{-\text{1}}$) is passed through a cation exchanger. The chloride ions obtained in solution were treated with excess of ${\text{AgNO}}_{\text{3}}$ to give 4.78 grams of AgCl (Molar mass=  ${\text{143.5\hspace{0.17em}gr\hspace{0.17em}mole}}^{-\text{1}}$). The formula of the complex is

• A

  $\left[\text{Co}{\left({\text{NH}}_{\text{3}}\right)}_{\text{6}}\right]{\text{Cl}}_{\text{3}}$

• B

  $\left[{\text{CoCl}}_{\text{2}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{4}}\right]\text{Cl}$

• C

  $\left[{\text{CoCl}}_{\text{3}}{\left({\text{NH}}_{\text{3}}\right)}_{\text{3}}\right]$

• D

  $\left[\text{CoCl}{\left({\text{NH}}_{\text{3}}\right)}_{\text{5}}\right]{\text{Cl}}_{\text{2}}$