Which symbol can be seen in the plenary hall of the German Bundestag?

EDITORIAL LEARNING AID

Why is this answer correct?

The large federal eagle, the heraldic animal of the Federal Republic, hangs in the plenary hall of the Bundestag. The imperial eagle and the imperial crown are symbols of the old German Empire and are not used. The Berlin flag is the symbol of the state of Berlin, not of the parliament.

Bundestag = federal eagle, not imperial eagle.

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