A stone is thrown upwards with a speed \['u'\] from the top of a tower. It reaches the ground with a velocity\['3u'\]. Find the height of the tower.

• A. \[\sqrt{3}\]                    
• B.        \[\frac{2{{u}^{2}}}{9}\]
• C. \[\frac{3{{u}^{2}}}{9}\]                                 
• D. \[\frac{4{{u}^{2}}}{9}\]