Which one of the following is categorised as a parasite in the true sense?

In an intertidal area,when all starfish were removed,more than $Q$ species of invertebrates became extinct within a year due to $P$.

Mycorrhiza is an example of which of the following?

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 $C$.

Which one of the following is not a matching pair of certain organism$(s)$ and the kind of association?

What is brood parasitism? Explain with the help of an example.