A 6-Kg Object Is Moving to the Right at 4

Multiple Choice

A 6-kg object is moving to the right at 4 m/s and collides with a 4-kg object moving to the left at 6 m/s.The objects collide and stick together.After the collision,the combined object:

A) has the same kinetic energy that the system had before the collision.
B) has more kinetic energy than the system had before the collision.
C) has no kinetic energy.
D) has less momentum than the system had before the collision.