A Key Conduit of "Enlightened" American Political and Moral Ideas

A key conduit of "enlightened" American political and moral ideas back to Europe came in the form of

A) returning British prisoners of war.
B) the hundreds of literate and influential French army and navy officers who had fought on the American side during the Revolutionary War.
C) European nobles returning from expeditions to the new American frontier.
D) missionary priests returning from evangelical campaigns deep in the U.S.back country.
E) official proclamations sent to the governments of Europe by George Washington.