- A Chordates
- B the phylum Annelida
- C only Arthropoda
- D a set of poriferans
Correct answer: A. Chordates
Explanation: Gill slits at some life stage is a chordate feature.
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.