Urea is urea is insoluble in water the primary nitrogenous waste product of humans the primary nitrogenous waste product of most birds the primary nitrogenous waste product of most aquatic invertebrates

There are choices for this question namely:

A) insoluble in water
B) the primary nitrogenous waste product of humans
C) the primary nitrogenous waste product of most birds
D) the primary nitrogenous waste product of most aquatic invertebrates

The correct answer is "the primary nitrogenous waste product of most birds" This is because the protein metabolized in birds, primarily the nitrogenous group in the protein, turns into the toxic compound ammonia. Ammonia is then organified to urea through the urea cycle and then excreted by birds.