1. Why did the United States push for control of the Oregon Country?

Question

increased American settlement in the Pacific Northwest

increased threat of British attacks on the Louisiana Territory

discovery of gold in the Rocky Mountains

need for more territory north of the Missouri Compromise

i think it is A

Answer 1

A is the best answer of those listed. President Polk subscribed to the idea of "manifest destiny", which mandated neat borders from the Atlantic to the Pacific, and British control of all or part of Oregon territory cut into that.