Competitive exclusion is most likely to occur between two (A) closely related species occupying different niches (B) closely related species occupying the same niche (C) related species occupying different habitats (D) unrelated species occupying different niches (E) populations of the same species

Closely related species occupying the same niche.

Explanation:

Competitive exclusion principle states that the two species cannot exist together if they share the same resources. The one species completely exclude the other species from their niche.

Competitive exclusion principle generally occurs between the species that occupy the same niche and are closely related with each other. The competitive exclusion principle first explained between the species P. aurelia and P. caudatum.

Thus, the correct answer is option (B).