Answer: Pisces.
- A Pisces
- B the class Mammalia
- C only class Aves
- D a group Reptilia
Correct answer: A. Pisces
Explanation: Fishes (Pisces) have a two-chambered heart.
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.