At which aquatic ph do all fish in lakes die ?
a. 4.2
b. 6.0
c. 5.5
d. 4.5

The answer is 4.2. (5.0 is kinda close to the PH of regular water, 5.5 is even closer) 4.2 is close to the PH of muriatic acid.

The writer could assert Taxonomy. Which is responsible for many scientific classifications and influences in various field of life sciences or biology.  Evidences that Taxonomy uses to group or categorizes species range from
1.       "Fossil Records
2.       Comparative anatomy
3.       Comparative embryology
4.       Biochemical information
5.       Cellular structure
6.       Behavior"
We also suggest that taxonomy has played various roles mainly in many aspects in Zoology, Botany, Anatomy and Physiology –aspects that include animal and human structures and functions. As the biotic community is so diverse it is classified to Biodiversity and the existence of properly assorting by set standard.