What is the nature of the interaction between methanogens and cattle?

$A$ : Fig species and wasp have a tight one-to-one relationship.
$R$ : Angiosperms and insects are coevolved to perform a plant-pollinator interaction.

Describe commensalism.

The given figure shows . . . . . . .

The most successful parasite is one that:

Observe the set of $4$ figures $A$,$B$,$C$ and $D$ and answer the following questions:
$(i)$ Which one of the figures shows mutualism?
$(ii)$ What kind of association is shown in $D$?
$(iii)$ Name the organisms and the association in $C$.
$(iv)$ What role is the insect performing in $B$?