For a concept-based MCQ, read this case: a sea star and a chordate are discussed together in a phylogeny lecture even though one is an invertebrate. Select the strongest explanation. (265)

Echinoderms and chordates are deuterostomes. Their embryological characters link them despite very different adult body forms. This question is designed as a comparison-based item to reduce thin-content style repetition and improve conceptual depth.