Predation,parasitism,and commensalism share a common characteristic,which is $.......$

Match Column-$I$ with Column-$II$ and select the correct option.

Column-$I$	Column-$II$
$(a)$ Yucca moth	$(i) \,(+, 0)$
$(b)$ Orchid	$(ii) \,(+, -)$
$(c)$ Hermit crab	$(iii) \,(+, +)$
$(d)$ Plasmodium	$(iv) \,(+, -)$

Given below are two statements:
Statement $I$: Gause's competitive exclusion principle states that two closely related species competing for different resources cannot exist indefinitely.
Statement $II$: According to Gause's principle,during competition,the inferior will be eliminated. This may be true if resources are limiting.
In the light of the above statements,choose the correct answer from the options given below :

In an aquarium,two herbivorous species of fish are living together and feeding on phytoplanktons. As per the Gause's Principle,one of the species is to be eliminated in due course of time,but both are surviving well in the aquarium. Give possible reasons.

Which of the following is an example of a positive interaction in a population?

Describe commensalism.