Economic structuralism, on the other hand, is concerned with the international division of labor created by the capitalist system. It sees that the division of labor is unfair, creating categories of rich and poor people, as well as rich and poor nations, at the macro level. Within the structuralist approach, there are actually two sub-approaches: the Marxist approach, which rejects capitalism completely, and the dependency approach, which aims to reform it. Particularly Karl Marx (1818-1883) and Friedrich Engels (1820-1895) created a great amount of literature outlining a theoretical critique of capitalism. The best place to look for details would be Marx and Engels’ The Communist Manifesto (1848) or Marx’s The Capital (1867).

As also understood from the information given, the correct answer is D. Karl Marx and Friedrich Engels can be said to be the main theorists of economic structualism approach. Adam Smith and David Ricardo formulated economic liberalism approach. Alexander Hamilton and Friedrich List can be said to be main theorists of economic nationalism.