Wie wird der Beitritt der DDR zur Bundesrepublik Deutschland im Jahr 1990 allgemein genannt?

Why this is the correct answer

When East Germany (the GDR) formally joined the Federal Republic on 3 October 1990, this historic event became known as German Reunification. It ended 45 years of division that had followed World War II and the subsequent Allied occupation. Reunification Day is still celebrated each year as Germany's national holiday.