Which of the following statements is true of the Berlin Wall? Select all that apply. (Pick AT LEAST two options can be more)
a. The Berlin Wall remained in place for 10 years.
b. One reason the wall was built is because people were fleeing East Berlin in large numbers.
c. East and West Berliners could no longer freely travel between sectors unless they had special privileges.
d. The United States responded by bombing the wall builders.