Question: who is called the advocate of conflict theory
[{'answer': 'Karl Marx', 'provenance': [{'wikipedia_id': '266956', 'title': 'Conflict theories', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 9, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '266956', 'title': 'Conflict theories', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 458, 'bleu_score': 0.51275932496134, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2341616258330324880}, 'section': 'Section::::Abstract.'}]}]