Which statement best explains how the Lewis and Clark expedition was a result of U. S. foreign policy?

A. The United States studied Native Americans in order to
provide safe passage for the explorers.
B. The United States received territory as a result of a victory in
the French and Indian War.
C. The United States purchased land from France so it could
expand the size of the nation.
D. The United States proved its land claims to Europe by establishing the Corps of Discovery.