Question: who explored the southwestern portion of the louisiana purchase
[{'answer': 'Lieutenant Zebulon Pike , Jr.', 'provenance': [{'wikipedia_id': '269818', 'title': 'Pike Expedition', 'start_paragraph_id': 1, 'start_character': 316, 'end_paragraph_id': 1, 'end_character': 348, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '269818', 'title': 'Pike Expedition', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 904, 'bleu_score': 0.986797956037998, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16230134395174993912}, 'section': 'Section::::Abstract.'}]}]