Question: an example of a complex system in the u.s. is
[{'answer': 'the stock market', 'provenance': [{'wikipedia_id': '37438', 'title': 'Complex system', 'start_paragraph_id': 27, 'start_character': 193, 'end_paragraph_id': 27, 'end_character': 209, 'bleu_score': 1.0, 'section': 'Section::::Key concepts.:Adaptation.\n'}]}, {'provenance': [{'wikipedia_id': '37438', 'title': 'Complex system', 'start_paragraph_id': 27, 'start_character': 0, 'end_paragraph_id': 27, 'end_character': 496, 'bleu_score': 0.953902344573157, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7624498423228316555}, 'section': 'Section::::Key concepts.:Adaptation.\n'}]}]