Refers to the process by which national economies, politics, cultures, and societies become integrated with those of other nations around the world.
nato
league of nations
multinational government
globalization

The first two options, NATO and League of Nations are not processes, but organizations, so they can't be the correct answer.

Then, there isn't really a "Multinational Government", except if you call the EU structure like this (but not the official name).

The correct answer is : globalization, it's the process by which societies become integrated.