The relation between solubility (S) and solubility product (KSP) is as follows KSP=xx.y9.Sx+y where, x and y are the number of atoms/radicals of the given species. For M(OH)3 type species x=1 y=3 thus, KSP=11×33S3+1=27S4 Hence, solution (d) is the correct answer.