Eventually, homo erectus migrations were limited to certain areas; they could not inhabit certain areas because of a climatic change known as the pleistocene
which was:
a. a period of global warming
b. a period of changing extremes, from warm to cold
c. an ice age
d. an age of desertification (extreme dryness which killed off plant food resources)
e. all of the above, at different times

The correct answer will be option C- an ice age.

Explanation:

Pleistocene is the part of the geological time scale represented by the cold climate.

This epoch started about 2.6 million years ago and lasted till the last 12000 years. This epoch represented one of the major ice age earth seen in the history which was observed with the ice glaciers.

The species of human evolved during this epoch mainly and travelled and reached the whole world.

Thus, option C is the correct answer.

your answer should be c) enjoy!