I live in your small intestine. Pseudocoelum is present in my thread-like body. In which phylum will you include me?
Aschelminths or Nemathelminthes are either free-living or parasitic animals.
The Giant Intestinal roundworm species belonging to the phylum Nemathelminthes is an endoparasite living in the human intestine.
These roundworms cause a disease called Ascariasis.
They usually live inside the intestine and causes obstruction to the intestinal passage.
So, the correct answer is Nemathelminthes.