Animals of the phylum Nemathelminthes are characterized by the presence of pseudocoelom. Such a coelom does not arise from the mesoderm and is not lined by the peritoneum.Enterocoelom is a true coelom that arises by pinching of mesodermally lined pouches. Haemocoel term is used to describe the body cavity of arthropods and molluscs. Blood flows within this cavity and bathes the internal organs of the body. Thus, the correct answer is option B.