Answer:
D. Colonies were too costly to maintain and defend
Explanation:
After the World War II, there was a big wave of gaining independence among the African and Asian countries. These countries were colonies of the Western European colonial powers, such as the British Empire and France. The World War II though left these countries in ruins, economically badly damaged, and with depleted military forces. There focus was to rebuilding their countries, so they were no longer economically and military powerful to maintain the colonies, thus they started to grant them independence, which resulted in lot of new countries and significant change of the political map of the world.