karl marx developed the economic theory of\n○ socialism.\n○ capitalism.\n○ utopianism.\n○ communism.

Brief Explanations:

Karl Marx developed a critique of capitalism and theories related to socialism and communism. His economic analysis was centered on the exploitation within capitalism and the path - towards a communist society. Socialism was a stage on the way to communism in his view. He did not develop capitalism as an economic theory in a positive sense. Utopianism was criticized by Marx for being idealistic without a scientific basis. His economic theory was mainly about the transition from capitalism to communism with socialism as an intermediate stage.

Answer:

communism.