The correct option is D A species restricted to a small area due to the presence of a competitively superior species is found to expand its distributional range when the competing species is experimentally removed
Competition is a type of population interaction in which the fitness of one species is significantly lower in the presence of another species. It occurs when more than one species competes for the same resources that are limiting and usually has a negative effect on both the interacting species.
Gause’s ‘Competitive Exclusion Principle’ states that two closely related species competing for the same resources cannot coexist indefinitely and the competitively inferior one will be eliminated eventually. This holds true when the resources are limited.
But it has also been observed that the resources need not be limited for competition to occur. In interference competition, the feeding efficiency of one species might be reduced due to the interfering and inhibitory presence of the other species, although the resources are abundant.
Competitive release is another evidence for the occurrence of competition in nature. A species restricted to a small geographical area because of the presence of a competitively superior species, is found to expand its distributional range when the competing species is experimentally removed. This is called competitive release.
Hence option d is correct.
However, certain mechanisms have been evolved by competing species that promote coexistence rather than exclusion.
For example, MacArthur showed that five closely related species of insectivorous birds called warblers that lived on the same tree were able to avoid competition and co-exist due to behavioural differences in their foraging activities. They are partitioning a limiting resource -- their supply of insects and is hence called ‘resource partitioning’. It allows them to coexist despite competition.