Assertion: `BeSO_(4) and MgSO_(4)` are insoluble in water.
Reason: `Be^(2+) and Mg^(2+)` have low hydration enthalpies.
A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false.
D. If both assertion and reason are false.