Among the choices provided, Fungi exhibit the highest species diversity. In the global distribution of biodiversity, Fungi represent a vast group of eukaryotic organisms with approximately 100,000 to 150,000 described species, though estimates suggest the actual number could be as high as 1.5 to 5 million. In biological studies (specifically according to NCERT classifications used in competitive exams like NEET), the number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles, and mammals.

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