Answer: Kingdom
Step-by-step explanation:
Life is grouped in a hierarchy called the Taxonomic rank. The higher a classification, the more organisms it would contain. On this scale, Kingdom is the second highest after Domain which means that of the options listed, it is the one with the greatest number of organisms.
Kingdoms include the sub-classifications: (Animalia, Plantae, Fungi, Protista, Archaea/Archaebacteria, and Bacteria/Eubacteria). Animalia include all the animals you know which means that Kingdoms contain a lot of organisms.