Answer:
d. Cnidarians and comb jellies, only two germ layers are formed
Step-by-step explanation:
Diploplastic animals are the animals which do not have three germs layer so rather than three they are made up of only two germ layer which is ectoderm and endoderm. Mesoderm is absent in them so they do not have true coelom or body cavity.
So as cnidarians and comb jellies are formed from only two germ layers that are endoderm and endoderm, therefore, they are called diploblastic. Fish, amphibians, reptiles, and mammals are triploblastic animals. So the correct answer is d.