The Berlin Wall was built... secretly, by using a dinner party as cover to begin construction. directly through the middle of American controlled west Berlin. by continuing construction with very little support from the communist Soviet Union. by closing the border overnight and immediately beginning construction.

The Berlin Wall was built:

D. by closing the border overnight and immediately beginning construction.

Explanation:

The closing of the border was literally carried out overnight. East German soldiers laid down, on the night of August 12-13 of 1961, over 30 miles of barbed wire. Then, only two days afterward, authorities began the construction of the wall that would stay up for 28 years. The Berlin Wall was probably one of the most important symbols - and certainly a very real, tangible one - of the Cold War.

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explanation:

it b =a chorus ik for a fact