With respect to a frame fixed to the centre of mass of a two particle system, some statements are given in following options. Select the correct statement if the particles don’t have same velocity w.r.t. an inertial frame. 

• A

  The two particles may move in same direction

• B

  The two particles must move in opposite directions

• C

  The two particles may have perpendicular velocities

• D

  The two particles should have same momentum