Terrestrial Animals Do Not Excrete Nitrogen as Ammonia Because

Terrestrial animals do not excrete nitrogen as ammonia because

A) it takes more energy to convert nitrogen to ammonia than it does to convert nitrogen to urea.
B) they would lose necessary salts by excreting ammonia.
C) ammonia is very toxic to terrestrial animals.
D) ammonia is not stable and is quickly converted to urea.
E) ammonia is insoluble in water and cannot be excreted as urine.