Final answer:
The feature allowing only Managers and Group owners to create posts in a Chatter Group is a Moderated Group. It controls information flow and maintains focus within the group.
Step-by-step explanation:
The feature of a Chatter Group that allows only Managers and Group owners to create posts in the group is known as a Moderated Group. In a Moderated Group, managers and owners have exclusive rights to create new posts, thereby controlling the flow of information and discussions within the group. This feature is particularly useful for maintaining the focus of group communication and ensuring that only relevant and appropriate content is shared.