Question: what is the cause of smog in china
[{'answer': 'the burning of fossil fuels', 'provenance': [{'wikipedia_id': '9895897', 'title': 'Pollution in China', 'start_paragraph_id': 28, 'start_character': 140, 'end_paragraph_id': 28, 'end_character': 167, 'bleu_score': 1.0, 'section': 'Section::::Pollution statistics.:Industrial pollution.\n'}]}, {'provenance': [{'wikipedia_id': '9895897', 'title': 'Pollution in China', 'start_paragraph_id': 28, 'start_character': 0, 'end_paragraph_id': 28, 'end_character': 471, 'bleu_score': 0.97451705556073, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7171797167153500551}, 'section': 'Section::::Pollution statistics.:Industrial pollution.\n'}]}]