Answer: Cellular level.
- A Cellular level
- B the organ system level
- C a tissue-grade level
- D only organ level type
Correct answer: A. Cellular level
Explanation: Sponges show only the cellular level of organisation.
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.