Earthworm - Digestive And Excretory System

Excretion in invertebrates is achieved by organ systems suited to each animal's body plan, and NCERT specifies the structures present in Pheretima. The earthworm excretes and osmoregulates using segmentally arranged coiled tubules called nephridia, which occur in most body segments and remove nitrogenous wastes while balancing body fluids; three types, namely septal, integumentary and pharyngeal nephridia, are recognised. Malpighian tubules are the excretory organs of insects such as the cockroach, attached at the junction of midgut and hindgut, so they are not found in earthworms. Flame cells are the protonephridial units of flatworms like Planaria and do not occur in annelids. Green glands, also called antennal glands, are excretory organs of crustaceans such as prawns, again outside the earthworm body plan. As stated in NCERT Class 11, Chapter 7 (Structural Organisation in Animals), nephridia are the excretory organs of the earthworm. A comparative check confirms that among the listed options only nephridia match the segmental annelid arrangement described in the question.