Answer:
A- the Mississippi river
Explanation:
The Mississippi River is known for its longer length, which almost covered the United States from the edge of the north and cross to over the territory of the United States in the south.
Its source began from the state of Minnesota and passes down through ten states to the Gulf of Mexico.
Due to its length, straightness, and location, the Mississippi River is a physical feature that is used to divide the eastern and western United States.