A 50-G Ball Moving at 10 M/s in the +X

Multiple Choice

A 50-g ball moving at 10 m/s in the +x direction suddenly collides head-on with a stationary ball of mass 100 g.If the collision is perfectly elastic,what is the velocity of each ball immediately after the collision?

A) -3.3 m/s,+6.7 m/s
B) +3.3 m/s,-6.7 m/s
C) -6.7 m/s,+3.3 m/s
D) +6.7 m/s,-3.3 m/s