Which of the Following Presents the Primary Challenge That the Bering

Which of the following presents the primary challenge that the Bering Land Bridge represented the first route for the first humans in the New World?

A) the earliest occupations pre-date the presence of Beringia
B) many early occupations pre-date the presence of the Ice Free Corridor
C) there are no Upper Paleolithic sites in northern Asia at the time of first settlement
D) modern Native Americans are genetically unrelated to northern Asian populations
E) the technologically simplest way to enter is not on foot