Definition: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Input: In 1952, following a referendum, Baden, Württemberg-Baden, and Württemberg-Hohenzollern merged into Baden-Württemberg. In 1957, the Saar Protectorate rejoined the Federal Republic as the Saarland. German reunification in 1990, in which the German Democratic Republic (East Germany) ascended into the Federal Republic, resulted in the addition of the re-established eastern states of Brandenburg, Mecklenburg-West Pomerania (in German Mecklenburg-Vorpommern), Saxony (Sachsen), Saxony-Anhalt (Sachsen-Anhalt), and Thuringia (Thüringen), as well as the reunification of West and East Berlin into Berlin and its establishment as a full and equal state. A regional referendum in 1996 to merge Berlin with surrounding Brandenburg as "Berlin-Brandenburg" failed to reach the necessary majority vote in Brandenburg, while a majority of Berliners voted in favour of the merger.
Output:
How did Baden-Württemberg form?