What was the United States’ claim to the Oregon Territory based on? Question 3 options:

a) The Lewis and Clark Expedition

b) It was part of the Louisiana Purchase.

c) It was part of the Mexican Cession.

d) Captain Robert Gray’s exploration of the mouth of the Columbia River.

a) The Lewis and Clark Expedition

Explanation:

The U.S. claim was based on the explorations of Lewis and Clark and on the establishment of trading posts set up by John Jacob Astor's Pacific Fur Company, such as Astoria at the mouth of the Columbia River. Great Britain based its claim, in part, on James Cook's exploration of the Columbia River.

d. migration