Which of the following complexes is used to be as an anticancer agent?

• A

  $mer-\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_3{\mathrm{Cl}}_3\right]$

• B

  $\text{ cis-[ }\left[{\mathrm{PtCl}}_2{\left({\mathrm{NH}}_3\right)}_2\right]$

• C

  $\mathrm{cis}-{\mathrm{K}}_2\left[{\mathrm{PtCl}}_2{\mathrm{Br}}_2\right]$

• D

  ${\mathrm{Na}}_2{\mathrm{CoCl}}_4$