Select the Platyhelminthes which is free living.

 

Concept: Platyhelminthes or flatworms live in a variety of habitats.
They can be found in marine water, freshwater and terrestrial and free-living organisms.
Platyhelminthes also involve parasitic flatworms that live in the host.
Planaria are found in freshwater, they are free living.
Tapeworm and Flukes are parasites, they are not free living organisms.
Hence, option C is the correct answer.