Throughout human history, major migrations have been spurred by sharp decreases in the availability of food caused by hazards or changes in climate For example, the Choose
was the result of a drought and wind-driven erosion. The Choose...
on the
other hand, was caused by a fungal disease that infected an important crop.

Choose the best explanation of the difference between evolution and natural selection. a. natural selection is the idea that species change over time, and evolution is the idea that our world changes over time. b. evolution is the idea that species change over time, and natural selection is the idea that nature changes over time. c. natural selection is the idea that species change over time, and evolution is the idea that the species' food source also changes over time. d. evolution is the idea that species change over time, and natural selection is a mechanism by which evolution takes place.