Consider the following statements : A. Aschelminthes are characterized by the presence of a true coelom. B. Metamerism and a true coelom are characteristic features of Annelids. C. Platyhelminthes have a body cavity completely lined by mesoderm. D. Echinoderms possess a pseudocoelom in their adult stage. Choose the correct answer from the options given below :

Step-by-step solution

Statement A is incorrect because Aschelminthes are pseudocoelomates, meaning their body cavity is not completely lined by mesoderm. Statement B is correct because Annelids are characterized by metameric segmentation and the presence of a true coelom. Statement C is incorrect because Platyhelminthes are acoelomates and lack a body cavity. Statement D is incorrect because Echinoderms are true coelomates, not pseudocoelomates. Answer: B only