The correct order of solubility (in water) is  ${\mathrm{SrSO}}_4<{\mathrm{CaSO}}_4<{\mathrm{MgSO}}_4<{\mathrm{BeSO}}_4$ Sulphates become less soluble as we move down the group because they begin to generate precipitates.

Hence ${\mathrm{SrSO}}_4<{\mathrm{CaSO}}_4<{\mathrm{MgSO}}_4<{\mathrm{BeSO}}_4$

Energy from solutions is lower than energy from water.

Also, the correct order of solubility (in water) are

$\mathrm{NaF}<\mathrm{KF}<\mathrm{RbF}<\mathrm{CsF}$

$\mathrm{Ba}(\mathrm{OH}{)}_2>\mathrm{Sr}(\mathrm{OH}{)}_2>\mathrm{Ca}(\mathrm{OH}{)}_2>\mathrm{Mg}(\mathrm{OH}{)}_2$

Hence, option D is correct.