For a concept-based MCQ, read this case: a sponge and a cnidarian are compared in class. the sponge differs most clearly because it has cellular-level organization and choanocyte-based filter feeding. Select the strongest explanation. (286)

Correct Answer: C

cellular-level organization with choanocytes

Sponges lack true tissues and use choanocytes for water currents and feeding. Cnidarians have tissue-level organization and cnidocytes, so these characters separate the two early animal phyla. This question is designed as a comparison-based item to reduce thin-content style repetition and improve conceptual depth.