Which present-day German federal state formerly belonged to the territory of the GDR?

EDITORIAL LEARNING AID

Why is this answer correct?

Mecklenburg-Vorpommern belonged to the Soviet occupation zone and was part of the GDR until 1990; the state was re-established in 1990. Hesse lay in the American zone and Schleswig-Holstein in the British zone. The Saarland belonged to the French zone.

Mecklenburg-Vorpommern belonged to the GDR.

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