Concept:Earthworms possess segmental excretory organs called nephridia.Explanation:• Contractile vacuole is for excretion/osmoregulation in protozoans.• Flame cell is the excretory structure in flatworms/Planaria.• Malpighian tubule is the excretory organ in insects.• Nephridium is the excretory organ found in earthworms.Answer:D. Nephridium