Concept:Earthworms are annelids that excrete most of their nitrogenous waste as urea.
Explanation:Because earthworms live in moist soil, they need to conserve water.
They convert harmful ammonia into less toxic urea before excretion.
Special excretory organs called nephridia remove this urea from the body.
Urea makes up about half of the earthworm’s nitrogenous waste.
Ammonia and other nitrogen compounds account for the remaining portion.
Uric acid is mainly the excretory product of birds and reptiles, not earthworms.
Answer:The main excretory product of earthworm is urea. Option C.