Question Detail
Question
Most animals in their embryonic stages are triboblastic except ______.
Correct Answer
Option A is the correct answer.
Detailed Explanation
Triboblastic animals (like mammals, echinoderms, and birds) develop three germ layers (ectoderm, mesoderm, endoderm) during embryogenesis. Porifera (sponges) are the simplest multicellular animals and are diploblastic or even considered to lack true tissues and germ layers, therefore not triboblastic.
Hint
Consider the simplest animal phylum listed, which often lacks complex tissue organization.