$12$ A constant horizontal pull acts on a sled on a horizontal frictionless ice pond. The sled starts from rest. When the pull acts over a distance $\backslash (\backslash$boldsymbol$\{$x$\}\backslash ),$ the sled acquires a speed $\backslash ($ v $\backslash )$ and a kinetic energy $\backslash ($ K $\backslash ).$ If the same pull instead acts over twice this distance,

the sled's speed will be $\backslash (2$ v $\backslash )$ and its kinetic energy will be $\backslash (2$ K $\backslash ).$

the sled's speed will be $\backslash (2$ v $\backslash )$ and its kinetic energy will be $\backslash ($ K $\backslash$sqrt$\{2\}\backslash ).$

the sled's speed will be $\backslash ($ v $\backslash$sqrt$\{2\}\backslash )$ and its kinetic energy will be $\backslash ($ K $\backslash$sqrt$\{2\}\backslash ).$

the sled's speed will be $\backslash ($ v $\backslash$sqrt$\{2\}\backslash )$ and its kinetic energy will be $\backslash (2$ K $\backslash ).$

the sled's speed will be $\backslash (4$ v $\backslash )$ and its kinetic energy will be $\backslash (2$ K $\backslash ).$