sikringbp and 36 others learned from this answer Lewis and Clark had three goals for their expedition: explore unknown territories, promote the sovereignty of the United States and its government, and establish trade with Native Americans. Lewis, Clark, and their men were successful in a large number of their dealings with Natives.
I can't see the lines that your question mentions but the rich farmland is what attracted settlers to Oregon. The gold rush was in California, and the only huge thing that was discovered in 1849 (option D) is the gold rush, no mention of an oil boom.
