A particle of mass m moves in the  XY-plane with a constant velocity ‘V’ along the straight line X'Y'. If the angular momentum of the particle with respect to origin O is LA when it is at A, and  LB when it is at B, then

Since the particle is moving on a straight line with a constant speed, the velocity will remain constantAs we know  L→=r→×mv→⇒L→=mvr r= Perpendicular distancev= Speedm= MassWe can see at point  A and  B the product  mvr is constant.Hence  L→A=L→B⇒LA=LB Therefore, the correct answer is (B).