Which diagram best represents an important part of eastern European history? ill give brainiest and 100 points (pls real answers)i really need help
A. World War II begins. Eastern Europe suffers serious damage.
B. World War I begins. Kosovo breaks away from Serbia.
C. Serbia attacks the Austro-Hungarian Empire. The Cold War begins.
D. The Soviet Union collapses. Communism spreads in eastern Europe. ​