The answer is C) They crossed the Bering Strait from Siberia to enter the Americas.
It is believed that the Bering Strait was not a waterway but either a land piece or an ice bridge. And some people in Russian and Middle Asian steppes migrated to North America.
A is false because when European colonists discovered them, they were not advanced. If they were advanced in the beginning, they should be advanced later too.
B is false because they were the only people in the continent. There wasn't another group to trade.
D is false because they didn't have the technology and the equipments to cross the Atlantic Ocean.
