Final answer:
The system challenged by the Commission requires manufacturers to market beer and soft drinks only in reusable containers. The National Agency for the Protection of the Environment approves the containers and can refuse approval based on certain criteria.
Step-by-step explanation:
The main feature of the system challenged by the Commission is that manufacturers must market beer and soft drinks only in reusable containers. The containers must be approved by the National Agency for the Protection of the Environment. The agency may refuse approval of new containers if they are not technically suitable for a return system or if the system does not ensure a sufficient proportion of containers are actually reused. If there is already an approved container of equal capacity available and suitable for the same use, approval may also be refused.