If a predator overexploits its prey in an ecosystem,what might be the consequences of this?

$A$ cuckoo laying eggs in the nest of other species of birds is an example of

Many parasites have evolved to be $A$ in such a way that both host and the parasite tend to $B$; that is,if the host evolves special mechanisms for rejecting or resisting the parasite,the parasite has to evolve mechanisms to $C$ and neutralize them,in order to be successful with the same host species.
Choose the correct option for $A$,$B$,and $C$.

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

Why do parasites exhibit parasitism?

Study the following four statements $(1-4)$ and select the two which are correct:
$(1)$ Lion eating deer and sparrow feeding on grain are ecologically similar in being consumers.
$(2)$ The predator starfish $Pisaster$ helps in maintaining species diversity of some invertebrates.
$(3)$ Predators often lead to the extinction of prey species.
$(4)$ Production of chemicals such as nicotine and strychnine by plants is a metabolic disorder.
Which two statements are correct?