The graph below shows the changes in two populations of herbivores in a grassy field. $A$ possible reason for these changes is that

Given below are two statements:
Statement $I$: Gause's competitive exclusion principle states that two closely related species competing for different resources cannot exist indefinitely.
Statement $II$: According to Gause's principle,during competition,the inferior will be eliminated. This may be true if resources are limiting.
In the light of the above statements,choose the correct answer from the options given below :

Which of the following mechanisms helps organisms protect themselves from predators?

Give scientific reasons: The members of a population do not breed with other populations.

Even a plant species,which makes its own food,cannot survive alone; it needs soil microbes to breakdown the $A$ matter in soil and return the $B$ nutrients for absorption. And then,how will the plant manage pollination without an animal agent? It is obvious that in nature,animals,plants and microbes cannot live in $C$ but interact in various ways to form a biological community. Choose the correct option for $A, B$ and $C$.

Statement-$I$: In the absence of predators,prey species population can decline and cause ecosystem instability.
Statement-$II$: Predators are prudent in nature and overexploit their prey.