When You Throw a Pebble Straight Up with Initial Speed $\sqrt { 2 }$

Multiple Choice

When you throw a pebble straight up with initial speed V,it reaches a maximum height H assuming there is no air resistance.At what speed should you throw it up vertically so it will go twice as high?

A) 16V
B) 8V
C) 4V
D) 2V
E) $\sqrt { 2 }$ V