Which group had been living in north america for thousands of years when other groups arrived?

The relationship between the English settlers and the American Indians from the beginning of the Jamestown Colony to the mid-1600s was mainly good. There was some conflict between the Settlers and the Native Americans, but for the most part, they lived peacefully next to one another and traded with each other. The trade between the two parties helped the Settlers gain knowledge and skills on how to live in the area. The Native Americans who lived near the Jamestown colony helped the settlers establish the Jamestown colony by teaching them how to hunt animals and grow crops. 

Ibelieve that the answer is (a).