In which case, depression freezing point is equal to cryoscopic constant for water?

${\mathrm{PtCl}}_4\mathbf{·}6{\mathrm{H}}_2\mathrm{O}$ can exist as a hydrated complex. $1 \mathrm{molal}$ aqueous solution has a depression in freezing point of $3.72°\mathrm{C}$. Assume, $100\%$ ionization and ${\mathrm{K}}_{\mathrm{f}} \left({\mathrm{H}}_2\mathrm{O}\right)=1.86 \mathrm{K} {\mathrm{mol}}^{-1} \mathrm{kg}$. Then the complex is:

Van't Hoff factors of aqueous solutions of three different solutes, $\mathrm{X}, \mathrm{Y}$ and $\mathrm{Z}$ are $1.8,$ $1.2$ and $2.5$, respectively. Hence, their order of molal concentration is

(Assume their freezing point is same.)