Answer:
The correct option is momentum is conserved
Step-by-step explanation:
A closed system is a system that is independent/free of external factors/force and does not exchange matter with its surrounding. Since a close system is free of external factors/force; acceleration is constant in it, mass is conserved in it and there will be changes in velocities of objects in the closed system.
This question actually seeks to test our knowledge of the law of momentum. The law of conservation of momentum states that the momentum of a closed system is conserved.