The statement that best describes the relationship that European communists and socialists had with their capitalist governments during World War II is:
European communists and socialists set up uneasy alliances with capitalists to defeat fascist and Nazi forces.
During the war, many communist and socialist parties in Europe formed coalitions with capitalist governments to combat the common enemy of fascism and Nazism, even though they often had ideological differences and mistrust towards the capitalist systems.