America's independence and expansion ·1783 treaty of paris ends american revolution ·1788 u. s. constitution ratified ·1803 louisiana purchase finalized · which event best completes this timeline? a) 1804 lewis and clark expedition begins b) 1808 congress bans the importation of slaves c) 1808 napoleon occupies spain d) 1812 war breaks out between the u. s. and great britain