What is the parliament for all of Germany called?

EDITORIAL LEARNING AID

Why is this answer correct?

The Bundestag is the parliament of the entire federation, elected by the people (Art. 38 GG). The Federal Assembly (a) only elects the Federal President, the People's Chamber (b) was the parliament of the GDR, and the Federal Court of Justice (d) is a court.

The parliament for all of Germany is the Bundestag.

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