Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ $3.1500 \ g$ of hydrated oxalic acid dissolved in water to make $250.0 \ mL$ solution will result in $0.1 \ M$ oxalic acid solution.
Reason $R:$ Molar mass of hydrated oxalic acid is $126 \ g \ mol^{-1}$.
In the light of the above statements,choose the correct 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 false but $R$ is true.
• C
  $A$ is true but $R$ is false.
• D
  Both $A$ and $R$ are true and $R$ is the correct explanation of $A$.