Correct Answer: Flatworms

Solution : The correct option is Flatworms.

Platyhelminthes, another name for flatworms, are a broad class of invertebrate organisms that inhabit freshwater, marine, and terrestrial settings. There are parasitic flatworms that can be endoparasites, living inside the bodies of their host animals, in addition to the many free-living flatworms. One well-known example of an endoparasitic flatworm is the tapeworm.