Given below are two Statements: One is labelled as Assertion A and the other is labelled as Reason R:
Assertion A: During the boiling of water having temporary hardness, \( \mathrm{Mg(HCO_3)_2} \) is converted to \( \mathrm{MgCO_3} \).
Reason R: The solubility product of \( \mathrm{Mg(OH)_2} \) is greater than that of \( \mathrm{MgCO_3} \).
In the light of the above statements, choose the most appropriate answer from the options given below: