Which level of taxonomy has the fewest organisms?

-domain

-kingdom

-genus

-species

The question is asking Which level of taxonomy has the fewest organisms? - therefore we have to choose the smallest group. This is the species, for example dogs are a species. then they form a genus together with Coyotes, and they they formgom with all other animals. Finally all eukaryotes are in the domain with dogs. So the smallest group is the species - only the dogs here in this example