Answer: Reptilia.
- A Amphibia
- B Reptilia
- C Aves
- D Mammalia
Correct answer: B. Reptilia
Explanation: Most reptiles have a three-chambered heart, but crocodiles are an exception, possessing a four-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.