Question: what was the cause of uncle toms cabin
[{'answer': 'anti-slavery', 'provenance': [{'wikipedia_id': '71989', 'title': "Uncle Tom's Cabin", 'start_paragraph_id': 1, 'start_character': 51, 'end_paragraph_id': 1, 'end_character': 63, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '71989', 'title': "Uncle Tom's Cabin", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 219, 'bleu_score': 0.550578563366876, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9369509648011541034}, 'section': 'Section::::Abstract.'}]}]