Which of the following complexes produces three moles of silver chloride when its one mole is treated with excess of silver nitrate?

The following reactions are obtained,

$\left[\mathrm{Cr}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]{\mathrm{Cl}}_3\iff {\left[\mathrm{Cr}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{3+}\left(aq\right)+3{\mathrm{Cl}}^{-}\left(aq\right)$

${\mathrm{Cl}}^{-}$ present in ionization sphere will give precipitate with ${\mathrm{AgNO}}_3$.

$3{\mathrm{Cl}}^{-}+3{\mathrm{Ag}}^{+}\to 3\mathrm{AgCl}$

So, one mole of complex will give three moles of $\mathrm{AgCl}$ precipitate.

Hence correct option is D.