Your answer is D: Common.
Africa started to be decolonized ~1945 - 1960, so i believe it was
C. the end of world war II
i'm not so sure tho
but hope this helps
During the first twenty years of the twentieth century china went trough political turmoil as seen by the people of the Republic of China, themselves. It also seen by other nations the way its economy and international relations are concerned. But nevertheless, China was still able to manage their economy and being one of the big nations.
This might help! :-)
http://www.loc.gov/teachers/classroommaterials/connections/slavery/file.html
