Question: who was in charge of building the hoover dam
[{'answer': 'Six Companies , Inc.', 'provenance': [{'wikipedia_id': '14308', 'title': 'Hoover Dam', 'start_paragraph_id': 22, 'start_character': 25, 'end_paragraph_id': 22, 'end_character': 48, 'bleu_score': 1.0, 'section': 'Section::::Construction.:Labor force.\n'}]}, {'provenance': [{'wikipedia_id': '14308', 'title': 'Hoover Dam', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 713, 'bleu_score': 0.929969208847466, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16307480777051011186}, 'section': 'Section::::Abstract.'}]}]