Appalachian Mountains were widely known for their extension between the region of Newfoundland and Labrador in Canada to central Alabama in the United States. They span about 3,200 kilometers, and the study shows they have been existing since more than 400 million years ago, during the period known as Ordovician period.
Hence, based on the information in the question, the right answer is option A. Appalachian Mountains
It was a water supply for the civilizations within the two rivers. The land was also very fertile and it made it easy to grow food. Lots of vegetation grew there.
