Question: when did the western black rhino become extinct
[{'answer': '2011', 'provenance': [{'wikipedia_id': '7687984', 'title': 'Western black rhinoceros', 'start_paragraph_id': 1, 'start_character': 166, 'end_paragraph_id': 1, 'end_character': 170, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '7687984', 'title': 'Western black rhinoceros', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 501, 'bleu_score': 0.9408228243926111, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9404869208099864684}, 'section': 'Section::::Abstract.'}]}]