Question Detail
Question
Most animals in their embryonic stages are triboblastic except
Correct Answer
Option B is the correct answer.
Detailed Explanation
Triboblastic animals (triploblasts) develop from three germ layers (ectoderm, mesoderm, and endoderm). Mammals, Aves (birds), and Echinoderms are all triboblastic. Porifera (sponges) are the simplest multicellular animals and are diploblastic or lack true tissues and germ layers, thus not triboblastic.
Hint
Consider the evolutionary complexity and germ layer development of each group.