A body of mass m moving along a straight line collides with a body of mass nm which is also moving with a velocity ku in the same direction. If the first body comes to rest after the collision, then the velocity of second body after the collision would be nv (1+nk) (1-nk) v (c)- n (a)- nv (1-nk) (b)- (1+ nk)v (d) n