Question: on which river did the exploration of the louisiana purchase begin
[{'answer': 'Missouri River', 'provenance': [{'wikipedia_id': '17615', 'title': 'Lewis and Clark Expedition', 'start_paragraph_id': 4, 'start_character': 282, 'end_paragraph_id': 4, 'end_character': 296, 'bleu_score': 1.0, 'section': 'Section::::Overview.\n'}]}, {'answer': 'the Missouri River', 'provenance': [{'wikipedia_id': '17615', 'title': 'Lewis and Clark Expedition', 'start_paragraph_id': 4, 'start_character': 278, 'end_paragraph_id': 4, 'end_character': 296, 'bleu_score': 1.0, 'section': 'Section::::Overview.\n'}]}, {'provenance': [{'wikipedia_id': '17615', 'title': 'Lewis and Clark Expedition', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17512598116228050867}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '17615', 'title': 'Lewis and Clark Expedition', 'start_paragraph_id': 18, 'start_character': 13, 'end_paragraph_id': 18, 'end_character': 455, 'bleu_score': 0.7138128458552161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17512598116228050867}, 'section': 'Section::::Journey.:Departure.\n'}]}, {'provenance': [{'wikipedia_id': '17615', 'title': 'Lewis and Clark Expedition', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 505, 'bleu_score': 0.8097592800698861, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17512598116228050867}, 'section': 'Section::::Overview.\n'}]}, {'provenance': [{'wikipedia_id': '17615', 'title': 'Lewis and Clark Expedition', 'section': 'Section::::Overview.\n', 'start_paragraph_id': 4, 'end_paragraph_id': 4, 'meta': {'evidence_span': ['One of Thomas Jefferson\'s goals was to find "the most direct and practicable water communication across this continent, for the purposes of commerce." He also placed special importance on declaring US sovereignty over the land occupied by the many different Indian tribes along the Missouri River, and getting an accurate sense of the resources in the recently completed Louisiana Purchase. The expedition made notable contributions to science, but scientific research was not the main goal of the mission.', 'He also placed special importance on declaring US sovereignty over the land occupied by the many different Indian tribes along the Missouri River, and getting an accurate sense of the resources in the recently completed Louisiana Purchase.', 'One of Thomas Jefferson\'s goals was to find "the most direct and practicable water communication across this continent, for the purposes of commerce." He also placed special importance on declaring US sovereignty over the land occupied by the many different Indian tribes along the Missouri River, and getting an accurate sense of the resources in the recently completed Louisiana Purchase. The expedition made notable contributions to science, but scientific research was not the main goal of the mission.']}}]}, {'provenance': [{'wikipedia_id': '18130', 'title': 'Louisiana', 'section': 'Section::::History.:Exploration and colonization by Europeans.\n', 'start_paragraph_id': 79, 'end_paragraph_id': 79, 'meta': {'evidence_span': ['and Tunica groups) and then followed the Mississippi River down to the Gulf of Mexico in 1543. Spanish interest in Louisiana faded away for a century and a half. In the late 17th century, French and French Canadian expeditions, which included sovereign, religious and commercial aims, established a foothold on the Mississippi River and Gulf Coast. With its first settlements, France laid claim to a vast region of North America and set out to establish a commercial empire and French nation stretching from the Gulf of Mexico to Canada. In', 'and Tunica groups) and then followed the Mississippi River down to the Gulf of Mexico in 1543. Spanish interest in Louisiana faded away for a century and a half. In the late 17th century, French and French Canadian expeditions, which included sovereign, religious and commercial aims, established a foothold on the Mississippi River and Gulf Coast. With its first settlements, France laid claim to a vast region of North America and set out to establish a commercial empire and French nation stretching from the Gulf of Mexico to Canada. In']}}]}, {'provenance': [{'wikipedia_id': '1989580', 'title': 'Louisiana (New France)', 'section': 'Section::::Boundaries, settlement and geography.:Upper Louisiana "(Haute-Louisiane)".\n', 'start_paragraph_id': 13, 'end_paragraph_id': 13, 'meta': {'evidence_span': ['Upper Louisiana, also known as the Illinois Country, was the French territory in the upper Mississippi River Valley, including settlements and fortifications in what are now the states of Missouri, Illinois, and Indiana. French exploration of the area began with the 1673 expedition of Louis Joliet and Jacques Marquette, which charted the upper Mississippi. As noted above, Upper Louisiana was primarily settled by colonists from French Canada. There was further substantial intermarriage and integration with the local Illinois peoples. French settlers were attracted by the availability of arable farmland as well as by the forests, abundant with animals suitable for hunting and trapping.', 'Upper Louisiana, also known as the Illinois Country, was the French territory in the upper Mississippi River Valley, including settlements and fortifications in what are now the states of Missouri, Illinois, and Indiana. French exploration of the area began with the 1673 expedition of Louis Joliet and Jacques Marquette, which charted the upper Mississippi. As noted above, Upper Louisiana was primarily settled by colonists from French Canada. There was further substantial intermarriage and integration with the local Illinois peoples. French settlers were attracted by the availability of arable farmland as well as by the forests, abundant with animals suitable for hunting and trappin']}}]}, {'provenance': [{'wikipedia_id': '176840', 'title': 'History of Missouri', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ["The history of Missouri begins with settlement of the region by indigenous people during the Paleo-Indian period beginning in about 12,000 BC. Subsequent periods of native life emerged until the 17th century. New France set up small settlements, and in 1803 Napoleonic France sold the area to the U.S. as part of the Louisiana Purchase. Statehood for Missouri came following a compromise in 1820 that allowed slavery. Settlement was rapid after 1820, aided by a network of rivers navigable by steamboats, centered in the dominant city St. Louis. It attracted European immigrants, especially Germans; the business community had a large Yankee element as well. The Civil War saw numerous small battles and control by the Union. After the war, its economy became more diverse, and railroads, centered in Kansas City, opened up new farmlands in the west. In the early 20th century Progressive reforms sought to modernize state and local government and minimize political corruption. During the 20th century, Missouri's economy diversified further, and it developed a balanced agricultural and economic sector. By the 21st century manufacturing was fading, as service industries grew, especially in medicine, education and tourism. Agriculture remained profitable, as the farms grew larger and fewer people lived on them.", 'The history of Missouri begins with settlement of the region by indigenous people during the Paleo-Indian period beginning in about 12,000 BC. Subsequent periods of native life emerged until the 17th century. New France set up small settlements, and in 1803 Napoleonic France sold the area to the U.S. as part of the Louisiana Purchase. Statehood for Missouri came following a compromise in 1820 that allowed slavery.']}}]}]