A Very Massive Object Traveling at 10 M/s Strikes a Light

Multiple Choice

A very massive object traveling at 10 m/s strikes a light object, initially at rest, and the light object moves off in the direction of travel of the heavy object.If the collision is elastic, the speed of the lighter object is

A) 5.0 m/s
B) 10 m/s
C) 15 m/s
D) 20 m/s
E) Can't tell from the information given.