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

• A
  Both $A$ and $R$ are true but $R$ is not the correct explanation of $A$.
• B
  $A$ is true but $R$ is false.
• C
  Both $A$ and $R$ are true and $R$ is the correct explanation of $A$.
• D
  $A$ is false but $R$ is true.