A learner makes a note: a sea star larva swims with right and left sides before developing into a radial adult. The missing scientific idea is:

Correct Answer: C

bilateral larvae

Echinoderm larvae are bilaterally symmetrical, while adults become pentaradial. This supports the evolutionary relationship of echinoderms with other bilaterian animals. This MCQ belongs to the Echinodermata topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.