<u>Answer:</u>
Geologists have sorted earth’s history into different geologic time scale. They just clubbed it into time scales by observing the major changes in the life forms that existed on the earth. Inferring to the fossils found in rocks the time scale was calculated.
First era single cell animals were formed then formed the complex animals.Then Mesozoic era where it is known as the era of dinosaurs. Then the evolution of different species of life during Cenozoic era. These major changes found through fossils helped them to form the GTS.
Water! It is the source of all life.
I believe the answer you're looking for is Evolution.
Ans. (D). community.
In an ecosystem, a community can be defined as a association or group of organisms of two or more species that occupy the same region, in a particular time. For example, grasses, herbivores (such as deer), and carnivores (such as lion represent a community in a grassland ecosystem that affect each other.
As earthworms and robins belong to two different species, they will represent a community in a beech forest ecosystem.
Thus, the correct answer is option (D).
