Question: who led an expedition to explore the louisiana territory
[{'answer': 'Lewis and Clark', 'provenance': [{'wikipedia_id': '17615', 'title': 'Lewis and Clark Expedition', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 15, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '17615', 'title': 'Lewis and Clark Expedition', 'start_paragraph_id': 9, 'start_character': 0, 'end_paragraph_id': 9, 'end_character': 406, 'bleu_score': 0.8565799162656831, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14611989193890711273}, 'section': 'Section::::Preparations.\n'}]}]