A projectile is fired with velocity at an angle theta with the horizontal. At the highest point of its trajectory, it splits into three segments of masses, m, m, and 2m. The first part falls with zero initial velocity vertically downward, and the second part returns back via the same path to the point of projection. Then, just after the explosion, the velocity of the third part of mass 2m will be:
(A) cos theta
(B) 3/2 cos theta
(C) 2 cos theta
(D) 5/2 cos theta