The correct answer to this open question is the following
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Here we are talking about Marxist Criticism that studies the differences between social classes under the influence of his most important thinker, Karl Marx, and other important influences like Frederick Engels.
The conflict that can be seen between the values, the work champions, and those it portrays can be seen in the differences and problems generated by the Capitalist system in the economies and social classes.
This can be understood as a Social conflict issue that authors have studied by the way competition affects resources in the economy and has produced inequality in society.
So critics of Marxism have questioned the validity of Kark Marx's concepts and their applications in the economy of societies, based on the idea that a true form of socialism is idealistic and difficult to implement.