Competition for food,light,and space is most intense in which of the following scenarios?

For a limited resource, two closely related species compete for the same resource, which is known as $.........$, which keeps them in check in the environment.

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 $C$.

Which of the following can be truly considered a parasite?

Assertion : Animals adopt different strategies to survive in hostile environments.
Reason : Praying mantis is green in colour which merges with plant foliage.

In an association of two animal species,one is a termite which feeds on wood and the other is a protozoan $Trichonympha$ present in the gut of the termite. What type of association do they establish?