What is the general name given to pre-columbian native american cultures who constructed earthen structures for religious, burial, and/or ceremonial purposes?

Washington said that the united states would be "friendly and impartial" in regard to foreign conflict. what was his reason behind this statement? a jefferson and washington had determined the u.s. was too weak to wage war. b the u.s. had a treaty with both england and france, and was thus required to remain neutral. c france asked for the united states to stay out of the war, due to trade relationships. d a special envoy from england asked for strict neutrality on behalf of the united states.