$5.$ If we double the root$-$mean$-$square speed of the molecules of a gas, then

A$)$ its temperature will decrease by a factor of $\backslash (1/\backslash$sqrt$\{2\}\backslash ).$

B$)$ its temperature will decrease by a factor of $\backslash (1/2\backslash ).$

C$)$ its temperature will increase by a factor of $\backslash (\backslash$sqrt$\{2\}\backslash ).$

D$)$ its temperature will increase by a factor of $2.$

E$)$ its temperature will increase by a factor of $4.$