Concept:Endoparasites live inside the host body, while ectoparasites live on the host surface.Explanation:Roundworm, liver fluke, and cestode live inside the host, so they are endoparasites.A tick attaches to the outside of the host skin to feed on blood, making it an ectoparasite.Therefore, the organism that is not an endoparasite is the tick.Answer:C. Tick