In ancient times, whites were mainly distributed in Europe, but in modern times, whites became the main residents in North America and Oceania, which caused this phenomenon.

Analysis of test questions: According to historical facts, after the opening of the new air route, western European countries successively embarked on the road of colonial expansion, and Europeans began to look for wealth all over the world, which led to the phenomenon that whites became the main residents of North America and Oceania in modern times, so item A should be chosen.

Comments: the influence of colonial expansion:

(1) Going to the world: The capitalist world market has been further expanded, and more and more countries have been brought into the capitalist world system, which has promoted the integration of the world.

(2) For colonial countries, colonial expansion and plunder brought huge profits and vast overseas markets to Western Europe, accelerated the process of primitive accumulation of capital and promoted the development of capitalism.

(3) Colonies: ① The brutal slaughter, plunder and enslavement of colonies by colonialists brought profound disasters to the colonial people, resulting in long-term backwardness in Asia, Africa and Latin America; (2) Colonialism brought a high life.