Question

The Lewis and Clark expedition (1803–1806) was

important because it
(1) determined the route of the first transcontinental railroad
(2) opened an all-water route to the Gulf of Mexico
(3) removed the British threat from the
Northwest Territory
(4) increased understanding of the area included
in the Louisiana Purchase

Answer 1

There are several reasons why the Lewis and Clark expedition (1803–1806) was important, but the best option from the list would be "(4) increased understanding of the area included in the Louisiana Purchase"