Question: where is olduvai gorge located (what countries)
[{'answer': 'Tanzania', 'provenance': [{'wikipedia_id': '319452', 'title': 'Olduvai Gorge', 'start_paragraph_id': 1, 'start_character': 38, 'end_paragraph_id': 1, 'end_character': 46, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '319452', 'title': 'Olduvai Gorge', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 681, 'bleu_score': 0.8396023292775231, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6281020031678112591}, 'section': 'Section::::Abstract.'}]}]