I’d say (A) Allows users with common interest to share their views and streams
The FriendFeed Rooms feature launched a few years back lets anyone create an account depending on the privacy settings. This feature allows you to carry on with conversations without the entire FriendFeed community getting involved. It is like an own private area of FriendFeed where niche conversations take place privately between like-minded users. It can be limited to co-workers or family members involved in a project.