Answer: Cnidaria.
- A Porifera
- B Cnidaria
- C Ctenophora
- D Annelida
Correct answer: B. Cnidaria
Explanation: Hydra is a freshwater cnidarian (Coelenterata) that shows radial symmetry and a polyp body form.
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.