A 550-G Ball Traveling at 8

A 550-g ball traveling at 8.0 m/s undergoes a sudden head-on elastic collision with a 250-g ball traveling toward it also at 8.0 m/s. What is the speed of the 250-g mass just after the collision?

A) 15 m/s
B) 8.0 m/s
C) 4.0 m/s
D) 14 m/s
E) 0 m/s