According to the most widely accepted theory, why were newcomers to No

According to the most widely accepted theory, why were newcomers to North America eventually unable to return Siberia?

A) The Bering Land Bridge had been submerged.
B) The quality of the game they found living in North America made returning unattractive.
C) They were rejected by the peoples they left.
D) They were unable to find their way back across the wilderness.

ANSWER
A