Which document is Karl Marx best known for?

Karl Marx is best known for "The Communist Manifesto," which he co-authored with Friedrich Engels and published in 1848. This work outlines the principles of Marxism, advocating for the working class's role in overthrowing capitalist societies to establish a classless society. It critiques the capitalist system and calls for the unification of the proletariat against the bourgeoisie. The manifesto has had a profound impact on political thought and action, inspiring various movements and ideologies throughout history.

The other documents listed are significant in their own contexts but are attributed to different authors and focus on different ideologies. "The Social Contract," written by Jean-Jacques Rousseau, addresses the legitimacy of government and the social contract theory. "Mein Kampf," authored by Adolf Hitler, outlines his political ideology and plans for Germany, while "The Wealth of Nations" is a foundational text in economics written by Adam Smith, which discusses the nature of economic systems and free markets. Each of these works serves its own purpose, but "The Communist Manifesto" distinctly represents Marx's revolutionary ideas regarding class struggle and societal change.