$12)$ When you throw a pebble straight up with initial speed $\backslash ($ V $\backslash ),$ it reaches a maximum height $\backslash ($ H $\backslash )$ with no air resistance. At what speed should you throw it up vertically so it will go twice as high?

A$)16$ V

B$)8$ V

C$)4$ V

D$)2$ V

E$)\backslash (\backslash$sqrt$\{2\}$ V $\backslash )$

Answer: E