At constant pressure,hydrogen is having temperature of $327^{\large\circ}C$.Till what temperature is it to be cooled such that the rms velocity of its molecules becomes half of the earlier values

Question

$\begin{array}{1 1}(A)\;123^{\large\circ}C\\(B)\;-123^{\large\circ}C\\(C)\;-100^{\large\circ}C\\(D)\;0^{\large\circ}C\end{array}$