_________ have the smallest number of organisms with a maximum of common characteristics.

In the biological hierarchy (Kingdom → Phylum → Class → Order → Family → Genus → Species), Species is the most specific and smallest taxonomic rank. A species contains organisms with the maximum number of shared characteristics because it represents the finest level of classification. As you move up the hierarchy from species to kingdom, the number of common characteristics decreases while the number of organisms included increases. Therefore, Species has the smallest number of organisms but with maximum common characteristics.