Hint: Coelom is a body cavity, located in metazoans. Metazoans are animals that develop from an embryo with these three tissue layers. The three layers are ectoderm, mesoderm, endoderm. Coelom formation is formed by enterocoely. Both the mesoderm and coelom are formed at the same time.
The coelom is given in the above diagram belongs to roundworm. The kingdom Animalia of round worm is phylum nematoda. Body type of phylum nematoda is bilateral symmetry; their organization is triploblastic. Their body cavity is pseudocoelom. The cavity is located between the body wall and gastrointestinal cavity. The cavity located in the middle is called a pseudocoelom. This cavity is formed from mesoderm and endoderm. The internal organs are located in this cavity.
Form and function of roundworms:
Roundworms have specialized tissues and organs systems that carry out essential body function
In general, the body systems of free living roundworms tend to be more complex than those of parasitic forms. Roundworms reproduce sexually, most species of roundworm are dioecious.
Thus the correct answer is option ‘C’.
Note: triploblastic is endoderm, mesoderm, ectoderm. Nematode means thread in greek. Endoderm forms in the inner lining of organs, mesoderm forms into the organs. Ectoderm forms the exoskeleton. Mesodermal tissue goes on to the form blood, bone, gonads, kidney and other organs. Organisms possessing a true coelom are known as true coelomates.