Answer: Porifera.
- A Cnidaria
- B Porifera
- C Ctenophora
- D Platyhelminthes
Correct answer: B. Porifera
Explanation: Phylum Porifera includes sponges, which have numerous pores (ostia) and a cellular level of organization.
Moving across the animal phyla, body organisation becomes progressively more complex: from no symmetry and cellular organisation (Porifera) through radial/diploblastic (Cnidaria), bilateral/acoelomate (Platyhelminthes), pseudocoelomate (Nematoda), to a true coelom with full organ systems (Annelida and beyond).
Concept context
Phylum-level classification of the animal kingdom from Porifera to Chordata, based on body symmetry, coelom, and segmentation. One of the most example-heavy chapters for NEET.