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In some way , the idea of " human capital " is similar to Karl Marx 's concept of labor power : he thought in capitalism workers sold their labor power in order to receive income ( wages and salaries ) .
 person: Karl Marx
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Karl Marx 
Answer:
 person: Karl Marx