Number 3 is microorganisms.
The correct answer of the given question above would be option D. The option that did not occur during the Cenozoic era is the formation of the ozone layer. The ozone layer has long been there before any era since it is part of the earth's atmosphere. Hope this answer helps.
Nice because : Biotic potential is the ability of a population of living species to increase under ideal environmental conditions – sufficient food supply, no predators, and a lack of disease. An organism’s rate of reproduction and the size of each litter are the primary determining factors for biotic potential.
Answer:
absorption of oxygen
Explanation:
the others would not make sense so i think this is the answer
