$q,8)$ The root$-$mean$-$square speed of the molecules of an ideal gas is $v.$ The gas is now slowly compressed to one$-$half its original volume with no change in temperature. What is the root$-$mean$-$square speed of the molecules now?

A$.4v$

B$.2v$

C$.\frac{v}{\sqrt[\phantom{2}]{2}}$

D$.v.$

E$.\frac{v}{2}$