The correct option is B Competitive exclusion principle
Two or more species with same requirements cannot exist indefinitely in
the same area as sooner or later they come into competition for
possession of it. This is called as Gause's competitive exclusion
principle, which state that an ecological niche cannot be simultaneously
and completed occupied by established populations of more than one
species. Two species can live in same habitat but not in the same niche.
More siimilar the two niches are, severe the competition is. So, the
correct answer is 'Competitive exclusion principle'.