Killing an organism for feeding is known as:

An association of two species where both the partners derive mutual benefit from each other is known as:

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

Name the association in which one species produces a poisonous substance or a change in environmental conditions that is harmful to another species.

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:

In which kind of population interaction, one species is harmed whereas the other is unaffected?