Correct Answer - D
Sharks are not ammonotelic, but they are ureotelic animals, ureotelic animals excrete urea instead of ammonia as the major nitrogenous waste product. Sharks need to avoid water loss from body, thus they cannot excrete ammonia, as it requires enough water to be eliminated. sharks can retain so much urea in their blood that their blood osmotic pressure approaches that of sea water. This minimises water loss from their body to adjust to the concentrated saline water of the sea.
