Which of the following pairs of animal phyla are the most closely related? A. Annelids and flatworms B. Sponges and mollusks C. Echinoderms and arthropods D. Cnidarians and echinoderms
Annelids and flatworms is the pair of animal phyla that are the most related, whereas sponges and mollusks, echinoderms and arthropods, cnidarians and echinoderms are not.
