The correct option is D Flame cells
Flatworms (Platyhelminthes) and roundworms (Nematodes) have excretory structures called flame cells for excretion. Flame cells function like kidneys to remove wastes from the body.
Nephridia are excretory structures found in Annelids.
Kidneys are found in most of the vertebrates.
Malpighian tubules are found in Arthropods.