If the molar solubility (in $mol \cdot L^{-1}$) of a sparingly soluble salt $AB_4$ is $S$ and the corresponding solubility product is $K_{sp}$,then $S$ in terms of $K_{sp}$ is given by the relation:

• A
  $S = \left(\frac{K_{sp}}{128}\right)^{1/4}$
• B
  $S = \left(\frac{K_{sp}}{256}\right)^{1/5}$
• C
  $S = \left(256 K_{sp}\right)^{1/5}$
• D
  $S = \left(128 K_{sp}\right)^{1/4}$