B.Z.

The provided articles do not mention any organization called "B.Z." Therefore, it is impossible to provide a summary about it based on the given information. The articles focus on separate incidents in Berlin. One article details allegations of sexual assault at a youth center in Neukölln, reporting that girls had reported prior incidents before a group rape allegedly occurred. The other two articles describe escalated celebrations involving hundreds of high school students celebrating their upcoming graduation (Abitur). These celebrations resulted in arrests, damaged police vehicles, and police investigations into various incidents. These events are newsworthy due to the scale of the gatherings, the resulting disturbances, and the serious nature of the alleged crimes.