The state capital of Brandenburg is called …

EDITORIAL LEARNING AID

Why is this answer correct?

The state capital of Brandenburg is Potsdam; the Landtag and the state government are based there. Cottbus, Brandenburg an der Havel and Frankfurt (Oder) are other large cities in the state, but not the capital.

Potsdam with Sanssouci Palace is the capital.

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