The correct answer of the given question above would be the third option: THE EVOLUTION OF POPULATIONS OVER TIME. What is represented by the base of a phylogenic tree is the evolution of populations over time. It is also known as the evolutionary tree. This tree shows the evolutionary relationships among species.
Gram staining
Gram-positive turns pink or red
Gram negative turns dark blue or purple
Microbes. Bacteria, for example, convert nitrogen and carbon dioxide from the air into usable components that plants and animals can use as essential building blocks. A loss of all microbes would be terrible news for living organisms that can't create or take in these essential nutrients on their own.