Which of the following taxa includes the largest number of organisms?

In the biological hierarchy, the number of organisms increases as we move up to higher (broader) categories.The hierarchy is: $\text{Species}<\text{Genus}<\text{Family}<\text{Order}<\text{Class}<\text{Phylum}<\text{Kingdom}$.Among the given options, Phylum is the highest taxonomic rank, thus it encompasses the greatest diversity and number of organisms compared to Class, Order, or Genus.