Answer:
Option A, oxygen in the atmosphere
Explanation:
The highest level of oxygen reached during this phase of the geological cycle of earth. The oxygen level in Carboniferous period accounted for 35% as compared to 21% of oxygen in the atmosphere in present time.
Due to high oxygen content, the giant and wide varieties of terrestrial animal and plant species evolved. For example – size of insects and carwlies increased, plant became extremely giant, increase in number of tree ferns etc.
The answer is binary fission
We may lead to a presupposition that the researcher based its analysis on the environmental habitats of the organisms, moreover it can also be the almost identical but different morphological or physiological structures. There are many ways to classify an animal or base an animal, morphology, embryology, DNA and others.
