Answer: Hemichordata.
- A Cephalochordata
- B Urochordata
- C Hemichordata
- D Echinodermata
Correct answer: C. Hemichordata
Explanation: Hemichordata was earlier considered a subphylum of Chordata, but is now classified as a separate phylum since the presence of a true notochord in these animals is doubtful.
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.