The correct response is:
He sent Lewis and Clark on an expedition to learn about the geography of the West and look for a passage to the Pacific Ocean.
President Jefferson's decision to send Meriwether Lewis and William Clark on their famous expedition (1804-1806) after the Louisiana Purchase was crucial in increasing interest in the western territories, including Oregon. Their journey provided valuable information about the geography, resources, and potential for settlement in the West, which encouraged further exploration and eventual settlement in the Oregon Territory.