The solubility of the sulphates of group 2 decreases from Mg to Ba, whereas the solubility of the hydroxides increases. Which explanation is correct?

1. AWith the large sulphate anion the hydration enthalpy of the cation changes little while the lattice enthalpy falls rapidly; with hydroxide the reverse is true.
2. BWith the large sulphate anion the lattice enthalpy changes little down the group while the hydration enthalpy of the cation falls faster in magnitude; with the small hydroxide anion the lattice enthalpy falls faster than the hydration enthalpy.
3. CIn both series the lattice enthalpy rises down the group, but it rises more for hydroxides.
4. DIn both series the hydration enthalpy of the cation rises down the group, but it rises more for sulphates.