Define/Explain: Endoparasites.

There is more competition for survival between

Explain sexual deceit.

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 $B$?

Competition for light,nutrients,and space is most severe between:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Abingdon tortoise in Galapagos islands became extinct within a decade after goats were introduced.
Reason $R$: Goats were more efficient at browsing than Abingdon tortoise.
In the light of the above statements, choose the most appropriate answer from the options given below: