The correct answer is:
The end of the Cold War.
Explanation:
The reunification of Germany was possible due to the end of the Cold War. After the fall of the Berlin wall, Berlin was unified as a single city. In 1990 one year after the fall of the Berlin wall, negotiations between the United States, France, England and the Soviet Union made the reunification possible marking the end of the Cold War. The German Democratic Republic then became part of the Federal Republic of Germany.
