Three particles A,B and C of equal masses move with equal speeds v along the medians of an equilateral triangle. They collide at the centroid O of the triangle. After collision A comes to rest while B retraces its path with speed v. The velocity of C is then

 

• A

  v, direction $\overline{\mathrm{OA}}$ 

• B

  2v, direction $\overline{\mathrm{OA}}$

• C

  2v, $\overline{\mathrm{OB}}$

• D

  v, direction $\overline{\mathrm{BO}}$