Final answer:
Jefferson learned about the Louisiana Territory from the reports of the Corps of Discovery.
Step-by-step explanation:
Jefferson learned what was in the Louisiana Territory from the reports of the Corps of Discovery. The Corps of Discovery was a team of explorers led by Meriwether Lewis and William Clark who were sent by Jefferson to explore the western portion of the United States. They documented their findings in journals, maps, and sketches, providing detailed information about the landscapes, plants, animals, and Native American tribes they encountered. These reports were instrumental in Jefferson's understanding of the Louisiana Territory.
Learn more about Jefferson's knowledge of the Louisiana Territory