The correct answer is D, Hymenolepis diminuta.  This is a multicellular organism with a characteristic scolex and proglottids.  Baylisascaris procyonis and Toxocara cati are nematodes (roundworms), and Schistosoma masoni is a trematode (fluke).

Click here to open a new window with a table showing comparative diagnostic features of cestodes.  Close the new window to return to this page.