In August 1961, the Berlin Wall was erected A. by the United States in an effort to keep illegal immigrants from entering West Berlin and subsequently claiming
'freedom in Western Europe.
B. by the Soviet Union so that peoples from Eastern Bloc countries could not flee to West Berlin.
C. to separate Berlin from East Germany-a decision mutually agreed upon by the United States and the Soviet
Union.
D. by the United States so that East Germans could not enter West Berlin.