Answer: B. It represents the main route for settlers moving into the Oregon Territory.
Step-by-step explanation:
In the early 1800s Americans were encouraged to stretch the USA from the east coast to the west coast in what was called the Manifest destiny. The line above aided in this venture as it enabled people to reach Oregon to the west of the United States.
Rightfully named the Oregon Trail, the line went through four states and allowed hundreds of thousands of people to move to Oregon and other areas in western USA thereby paving the way for the assimilation of those territories into the United States.