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.

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure

they both go up but then go back down. they both end lower than they started. lastly, they both are competitive/the second on.

explanation: