What is the accession of the GDR to the Federal Republic of Germany in 1990 generally called?

EDITORIAL LEARNING AID

Why is this answer correct?

For the “Leben in Deutschland” test, connect “German reunification” with the meaning of the question. This is the answer marked as correct in the official key. “NATO eastern enlargement” is not part of the solution and points to a different issue. Learn the key term together with the complete correct answer instead of memorising only its letter.

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