Which of these is a district of Bremen?

EDITORIAL LEARNING AID

Why is this answer correct?

Hemelingen is a district of Bremen and lies east of the Weser. Altona belongs to Hamburg, Pankow to Berlin and Babelsberg to Potsdam, so they are not districts of Bremen.

Hemelingen lies east of the Weser; Altona belongs to Hamburg.

This translation and explanation are editorial learning aids. The official German wording and answer key govern the examination.