Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$
Assertion $(A) :$ At $10^{\circ} C$, the density of a $5\, M$ solution of $KCl$ [atomic masses of $K$ and $Cl$ are $39$ and $35.5\, g \,mol ^{-1}$ ]. The solution is cooled to $-21^{\circ} C$. The molality of the solution will remain unchanged.
Reason $(R):$ The molality of a solution does not change with temperature as mass remains unaffected with temperature.
In the light of the above statements, choose the correct answer from the options given below