Answer:
(c) The Appalachian Mountains begin to form.
Step-by-step explanation:
The Appalachian Mountains formed 480 million years ago.
These mountains formed in prehistoric time and they are found in the eastward side of North America. It is believed that they were as high as Rocky Mountain and the Alps but their altitude was reduced by erosion.
The mountain range is mostly found in the US but is also part of Canada. It is divided into different ranges with the highest part at the altitude height of 6,684 feet which is Mount Mithcell in North Carolina. This point is the highest in the United Stated east.