The coastal-route theory suggests that people may have first arrived in the Americas by crossing . A.) the open Pacific on a raft and reaching the coast of South America.

B.) the land bridge but spreading south along the Pacific coast instead of moving inland.

C.) from Greenland or Iceland in large ships and traveling south along the Atlantic coast.

D.) the arctic waters by boat and traveling south along the Pacific coast.

D. the arctic waters by boat and traveling south along the Pacific coast.

Explanation:

The coastal-route theory suggests humans may have first come to America by crossing the arctic waters and travelling towards the south along the Pacific coast, which involves the first settlement of the Americas. People might have travelled from Siberia to Alaska and the coast of North and South America.

the western roman empire flourished, but the eastern portion of the empire struggled.