Which of these is a district (Landkreis) in Thuringia?

EDITORIAL LEARNING AID

Why is this answer correct?

The Wartburgkreis lies in the west of Thuringia around the Wartburg castle near Eisenach. Ammerland belongs to Lower Saxony, Altötting to Bavaria and Nordfriesland to Schleswig-Holstein.

Wartburgkreis: the Wartburg near Eisenach, in western Thuringia.

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