Answer:
Option: B.) They were following herds of large mammals, such as mammoths and bison.
Explanation:
According to some scientist, the nomadic hunters might have moved to North America after following the herds of mammals, like Mammoth, Mastodons (now extinct) and Bison. The Nomadic hunters or people immigrated to the new land through Bering Land Bridge that connects Asia to America in about 12000 years ago.