What did the first americans have to depend on for their survival?

a) the environment
b) their enemies
c) dinosaurs
d) religious beliefs

The first Americans - this could be interpreted as the Native Americans who arrived, from Asia via Bering Strait, 12 000 years ago had to depend on their environment: the plants that grew in America, the animals they could find, and they had to devise ways to find those into food and shelter.