What Event Was an Important Cause of the Surge of Immigration

Multiple Choice

What event was an important cause of the surge of immigration to European countries such as Germany since the beginning of the 1990s?

A) the release of the last German colony in Africa in 1989
B) the expulsion of many foreign-born immigrants from France
C) an environmental disaster in the Balkans
D) Germany's mild climate
E) the collapse of the Soviet Union