Which of the following fails to explains why economic integration has never been easy to achieve or sustain, despite the strong economic and political arguments in support? （ ） A. While a nation as a whole may benefit significantly, certain groups may lose. B. No country has shown significant improvement because of economic integration. C. Countries fear a reduction of their political weight in the world because of economic integration. D. Linking neighboring economies and making them increasingly dependent on each other creates little incentives for political cooperation.