The salt is $M_{2}S{O}_4$.

The formation of ions for  $M_{2}S{O}_4$ with concentration will be:

So, the solubility product will be:

$K_{sp}={\left[M^{+}\right]}^2\left[S{O}_4^{2-}\right]$

$K_{sp}={\left[2s\right]}^2\left[s\right]$

$K_{sp}=4s^3$

Putting the value of Solubility product, we get:

  $3.2\times {10}^{-5}=4s^3$

  $s=\sqrt[3]{\frac{3.2\times {10}^{-5}}{4}}=2\times {10}^{-2}$

The maximum concentration of ${\mathrm{SO}}_4^2$-ion that could be attained in a saturated solution of this solid at $298 \mathrm{K}$ is $2\times {10}^{-2}\mathrm{M}$.

Therefore, the correct option is (D).