A syllabus groups Porifera, Cnidaria, Mollusca, Annelida, Arthropoda, and Echinodermata at the same major rank. The best answer is:

A phylum is a high taxonomic rank used to group animals that share a major body plan. Porifera, Cnidaria, Mollusca, Annelida, Arthropoda, and Echinodermata are examples of animal phyla. This MCQ belongs to the Classification topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.