The correct option is B Aschelminthes
Only phylum Aschelminthes are pseudocoelomates. They comprise of animals where the body cavity is present but it is not completely lined by mesoderm, but mesoderm is present as scattered pouches between ecto and endoderm.
Phylum Porifera and Platyhelminthes - acoelomates
Phylum Annelida - coelomate