Which of the following forms a set of complex and a double salt, respectively?
$\mathrm{CuSO}_4 \cdot 5 \mathrm{H}_2 \mathrm{O}$ and $\mathrm{CuCl}_2, 4 \mathrm{NH}_3$
$\mathrm{PtCl}_2 \cdot 2 \mathrm{NH}_3$ and $\mathrm{PtCl}_4 \cdot 2 \mathrm{HCl}$
$\mathrm{K}_2 \mathrm{PtCl}_2 \cdot 2 \mathrm{NH}_3$ and $\mathrm{KAl}\left(\mathrm{SO}_4\right)_2 \cdot 12 \mathrm{H}_2 \mathrm{O}$
$\mathrm{NiCl}_2 \cdot 6 \mathrm{H}_2 \mathrm{O}$ and $\mathrm{NiCl}_2\left(\mathrm{H}_2 \mathrm{O}\right)_4$
