Observe the following diagrams of invertebrates embryos illustrating the characteristics of the body plan.
Reference

Select the correct sequence which corresponds to the phyla represented with I, II, III, IV and V.

Options

A. `{:(" I"," II"," III"," IV"," V"),("Cnidaria","Platyhelminthes","Annelida","Nematoda","Arthropoda"):}`
B. `{:(" I"," II"," III"," IV"," V"),("Cnidaria","Platyhelminthes","Nematoda","Arthropoda","Annelida"):}`
C. `{:(" I"," II"," III"," IV"," V"),("Nematoda","Arthropoda","Platyhrlminthes","Cnidaria","Annelida"):}`
D. `{:(" I"," II"," III"," IV"," V"),("Annelida","Cnidaria","Arthropoda","Platyhrlminthes","Nematoda"):}`

Answer

B

Explanation

The embryo of animal I shows two germinal layers, ectoderm and mesoderm. This animal is diploblastic, it can be a poriferm and mesoderm. This animal is diploblastic, it can be a poriferan or cnidarian. The embroyos of all other animals have three germinal layers, the ectoderm, mesoderm and endoderm. These animals are triploblastic animals. They can be from Phylum Platyhelminthes to Phylum Mollusca. Embryos I and II have no coelom, III has pseudocoelom and IV and V have true coelom. Coelom is a fluid -filled cavity that forms the main body cavity of animals. it is formed by splitting of the mesoderm. Therefore, embryos I and II can be of poriferans, cnidarians, ctenophorans or platyhelminthes, embryo III is of nemathelminthes, whereas embryos of V shows internal divisions or segmentation in the body. Embryo V, thus is annelidan. So, we can conclude, embryo I is of cnidaria, embryo II is of platyhelminthes, embryo III is of namathelminthes, embryo IV is of arthropoda and embryo V is of annelida.