$9.$ Spring $\backslash$#$1$ has a force constant of $\backslash ($ k $\backslash ),$ and spring $\backslash$#$2$ has a force constant of $\backslash (2$ k $\backslash ).$ Both springs are attached to the ceiling, identical weights are hooked to their ends, and the weights are allowed to stretch the springs. The ratio of the energy stored by spring $\backslash$#$1$ to that stored by spring $\backslash$#$2$ is

A$.1$:$1.$

B$.1$:$2.$

C$.2$:$1.$

D$.\backslash (1$: $\backslash$sqrt$\{2\}\backslash ).$

E$.\backslash (\backslash$sqrt$\{2\}$: $1\backslash ).$