Which among the following molecule has maximum covalent character

${\mathrm{K}}^{+}, {\mathrm{Mg}}^{+2}$ ions have inert gas configuration;

${\mathrm{Cu}}^{+}, {\mathrm{Zn}}^{+2}$ ions have pseudoinert gas configuration ;

${\mathrm{Zn}}^{+2}$ ion is smaller with higher positive charge as compared to ${\mathrm{Cu}}^{+} \mathrm{ion}$