Two closely related species can co-exist indefinitely and violate the…

The correct answer is Option (2) → resource partitioning.

Option (1) eliminating the inferior species. — Incorrect. This is what Gause’s principle itself predicts: the competitively inferior species is eliminated. It is the end of co-existence, not a way to co-exist.

Option (2) resource partitioning. — Correct. The two species share the resource by using it at different times or in different ways.

Option (3) interacting with each other symbiotically. — Incorrect. In a symbiotic (mutualistic) interaction both species gain from each other, as in lichens. Two species that compete for the same resource are in a different relationship, and mutualism is not how competitors avoid competition.

Option (4) changing the area of grazing. — Incorrect. If one species moves to another area, the two are separated and no longer live together in the same place. MacArthur’s warblers stayed on the same tree and only fed in different ways.

NCERT Extract:
Population Interactions – “… Gause’s ‘Competitive Exclusion Principle’ states that two closely related species competing for the same resources cannot co-exist indefinitely and the competitively inferior one will be eliminated eventually. This may be true if resources are limiting, but not otherwise. More recent studies do not support such gross generalisations about competition. While they do not rule out the occurrence of interspecific competition in nature, they point out that species facing competition might evolve mechanisms that promote co-existence rather than exclusion. One such mechanism is ‘resource partitioning’. If two species compete for the same resource, they could avoid competition by choosing, for instance, different times for feeding or different foraging patterns. MacArthur showed that five closely related species of warblers living on the same tree were able to avoid competition and co-exist due to behavioural differences in their foraging activities.”