Why did the first Americans migrate to North America?

AThey were trying to find a warmer climate.
BThey were following their food source.
CTheir gods told them to migrate.
DTheir homes were destroyed by a flood.

Verified Answer :

The main reason why the first Americans migrate to North America was that "B) They were following their food source," since they came across from what is now Russia via the Bering Land Bridge.