Answer:
The magnitude and variety of the changes that occurred in the world’s political systems beginning in the early 20th century suggest the dimensions of the problem. Great empires disintegrated; nation-states emerged, flourished briefly, and then vanished; world wars twice transformed the international system; new ideologies swept the world and shook established groups from power; all but a few countries experienced at least one revolution and many countries two or more; domestic politics in every system were contorted by social strife and economic crisis;
Step-by-step explanation: