What is the interaction between two species called?

Match the Column-$I$ and Column-$II$:

Column-$I$	Column-$II$
$(P)$ Lichens	$(i)$ Parasitism
$(Q)$ Abingdon tortoise and goat	$(ii)$ Commensalism
$(R)$ Sea anemone and clown fish	$(iii)$ Competition
$(S)$ Human and liver fluke	$(iv)$ Mutualism

Identify the correct adaptations of parasites from the following list:
$a.$ Loss of unnecessary sense organs
$b.$ Presence of adhesive organs
$c.$ Presence of suckers
$d.$ High reproductive capacity
$e.$ Well-developed digestive system
Choose the correct option with respect to parasites.

Which of the following statements is incorrect?

$A$: An ecological niche is usually occupied by a single species.
$R$: More than one species can live in the same habitat.

Predators play an important role in: