The correct answer is B) The Rocky Mountains
Explanation:
The first map shows in colors the cultural regions that divided North America. In this, the Great Plains region is shown in yellow and this is located in the interior of the U.S. territory. On the other hand, the second map displays geographical features of the U.S. including important mountain ranges and water bodies. In this, the Rocky Mountains are shown in brown. Moreover, these mountains act as a border for the Great Plains, which are shown in yellow and are located to the east of the Rocky Mountains. Thus, the feature that forms the western boundary of the Great Plains is the Rocky Mountain.
