An aqueous solution of salt gives white precipitate with ${\mathrm{AgNO}}_3$ solution as well as with dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$. It may be :

The reactions are,

$\begin{array}{r}{\mathrm{BaCl}}_2+2{\mathrm{AgNO}}_3\to \underset{\text{ White ppt. }}{2\mathrm{AgCl}\downarrow }+{\mathrm{BaNO}}_3\\ {\mathrm{BaCl}}_2+{\mathrm{H}}_2{\mathrm{SO}}_4\to \underset{ }{ }+2\mathrm{HCl}\end{array}$

Here, only ${\mathrm{Na}}_2{\mathrm{SO}}_4$ does not give ppt. Thus, option C is correct.