A zoology teacher links echinoderms with chordates based on early embryonic development. The best answer is:

Correct Answer: A

deuterostome affinity

Echinoderms are deuterostomes, sharing developmental features with chordates such as blastopore fate and coelom formation patterns. This makes them important in phylogenetic study. This MCQ belongs to the Echinodermata topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.