Answer: Chondrichthyes.
- A Osteichthyes
- B Chondrichthyes
- C Amphibia
- D Cyclostomata
Correct answer: B. Chondrichthyes
Explanation: Chondrichthyes (cartilaginous fishes such as sharks and rays) have separate gill slits without an operculum, unlike Osteichthyes (bony fishes), which have gills covered by an operculum.
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.