A 1200 Kg Car Is Moving at 5

A 1200 kg car is moving at 5.0 m/s EAST. It strikes an 1800 kg car at rest. The cars undergo an elastic collision and move in the EAST or WEST direction. The velocity of the 1200 kg car after the collision is

A) 4.0 m /s EAST.
B) 1.0 m/s EAST.
C) 4.0 m/s WEST.
D) 1.0 m/s WEST.
E) 3.0 m/s EAST.