Here's a short story:

Berlin is the capital and the largest city of Germany as well as one of its 16 constituent states. With a population of approximately 3.7 million, Berlin is the second most populous city proper in the European Union and the seventh most populous urban area in the European Union. Located in northeastern Germany on the banks of the rivers Spree and Havel, it is the centre of the Berlin-Brandenburg Metropolitan Region, which has roughly 6 million residents from more than 180 nations. Due to its location in the European Plain, Berlin is influenced by a temperate seasonal climate. Around one-third of the city's area is composed of forests, parks, gardens, rivers, canals and lakes. 

First documented in the 13th century and situated at the crossing of two important historic trade routes, Berlin became the capital of the Margraviate of Brandenburg (14171701), the Kingdom of Prussia (1701–1918), the German Empire (1871–1918), the Weimar Republic (1919–1933) and the Third Reich (1933–1945). Berlin in the 1920s was the third largest municipality in the world. After World War II and its subsequent occupation by the victorious countries, the city was divided; East Berlin was declared capital of East Germany, while West Berlin became a de facto West German exclave, surrounded by the Berlin Wall (1961–1989) and East German territory. Following German reunification in 1990, Berlin once again became the capital of all of Germany. (End of story)

Provide your best guess for the following question. Give ONLY the guess, no other words or explanation.

For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>

Here are a few examples of questions and answers:

Question: How many states does Germany have?
Guess: 16

Question: What is one of them?
Guess: Berlin

Question: Is it the capital?
Guess: yes

Question: Is it the largest city in  Germany?
Guess: yes

Question: Is it the largest city in the EU?
Guess: no

Question: Is it the second most?
Guess: yes

Question: What rivers is it located on?
Guess: the rivers Spree and Havel

Question: Where in Germany is it located?
Guess: northeastern Germany

Question: What metro region is it in?
Guess: the Berlin-Brandenburg Metropolitan Region

Question: Is it in the European Plain?
Guess: yes

Question: How many residents does it have
Guess: roughly 6 million residents

Question: How much of the city is nature?
Guess: about 1/3rd

Question: When was the Margraviate of Brandenburg founded?
Guess: 1417

Question: the German Empire?
Guess: 1871–1918

Question: the Weimar Republic?
Guess: 1919–1933

Question: the Third Reich ?
Guess: 1933–1945

Question: When was the city divided?
Guess: After World War II

Question: By what?
Guess: by the victorious countries

Question: During what years?
Guess: 1961–1989

Now answer the following question in the same format.

Question: When was Germany reunified?

1990