Car A rear ends Car B, which has twice the mass of A, on an icy road at a speed low enough so that the collision is essentially elastic. Car B is stopped at a light when it is struck. Car A has mass m and speed v before the collision. After the collision:______

a. each car has half the momentum.
b. car A stops and car B has momentum m v.
c. car A stops and car B has momentum 3m v.
d. the momentum of car B is three times as great in magnitude as that of car A.
e. each car has half of the kinetic energy.