$A$ particle of mass $m$ moving with speed $2v$ collides with a mass $2m$ moving with speed $v$ in the same direction. After the collision,the first mass is stopped completely,while the second one splits into two particles each of mass $m$,which move at an angle of $45^o$ with respect to the original direction. The speed of each of the moving particles will be:

• A
  $v / (2\sqrt{2})$
• B
  $2\sqrt{2}v$
• C
  $\sqrt{2}v$
• D
  $v / \sqrt{2}$