Final answer:
The number of similarities between organisms increases as you move down the taxonomic pyramid because organisms within a particular level are more closely related to each other than to organisms in higher or lower levels.
Step-by-step explanation:
As you move down the taxonomic pyramid, the number of similarities between organisms at each level increases. This is because organisms within a particular level are more closely related to each other than to organisms in higher or lower levels. For example, at the domain level, the diversity of organisms is widest, but as you move down to lower levels such as kingdom, phylum, class, and so on, the organisms become more similar and share more characteristics. This is because they have a more recent common ancestor and have evolved from the same lineage.