Two carts (A and B), having spring bumpers, collide as shown. Cart A has a mass of 2 kg and is initially moving to the right. Cart B has a mass of 3 kg and is initially stationary. When the separation between the carts is a minimum:
A) cart B is still at rest
B) cart A has come to rest
C) the carts have the same momentum
D) the carts have the same kinetic energy the kinetic energy of the system is at a minimum