Which phylum has most members that are parasitic?

The correct answer is Platyhelminthes.

Platyhelminthes is a phylum of flatworms, which includes tapeworms, flukes, and planarians. Most platyhelminthes are parasitic, and they can infect a wide variety of hosts, including humans, animals, and plants. Some of the most common platyhelminth parasites include:

* Tapeworms: Tapeworms are long, segmented worms that can live in the intestines of humans and animals. They can cause a variety of symptoms, including abdominal pain, diarrhea, and weight loss.

* Flukes: Flukes are flat, leaf-shaped worms that can infect the liver, lungs, or intestines of humans and animals. They can cause a variety of symptoms, including fever, abdominal pain, and diarrhea.

* Planarians: Planarians are free-living flatworms that can be found in freshwater habitats. They are not parasitic, but they can sometimes be found in human homes, where they can be a nuisance.