The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
Nationalism, colonialism, and imperialism, and the Cold War influenced the contemporary map of the 20th century in that those elements created separation and division between countries. Wealthier nations used their expansionists ideas to invaded other nations, ethnicities created major separations and international conflicts, the greed of powerful nations exploited underdeveloped nations, polarized people, and confronted one political side against the other.
Nationalistic ideas radicalized ideas of "my country is better than yours and that gives the right to impose my conditions..." and this absurd idea was the foundation of more separation and exploitation of poor nations.