Question: when did the japanese river otter become extinct
[{'answer': 'August 28 , 2012', 'provenance': [{'wikipedia_id': '3735581', 'title': 'Japanese river otter', 'start_paragraph_id': 1, 'start_character': 589, 'end_paragraph_id': 1, 'end_character': 605, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '3735581', 'title': 'Japanese river otter', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 924, 'bleu_score': 0.9436601959653331, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 586502001400767985}, 'section': 'Section::::Abstract.'}]}]