Two Identical 7-Kg Bowling Balls Roll Toward Each Other

Multiple Choice

Two identical 7-kg bowling balls roll toward each other.The one on the left is moving at +4 m/s while the one on the right is moving at −4 m/s.What is the velocity of each ball after they collide elastically?

A) Neither is moving.
B) −4 m/s,+4 m/s
C) +4 m/s,−4 m/s
D) −14 m/s,+14 m/s
E) ​+14 m/s,-14 m/s