The correct option is A Urea
The nitrogen compounds through which excess nitrogen is eliminated from organisms are called nitrogenous wastes. They are ammonia, urea, uric acid and creatinine. All of these nitrogenous wastes are produced from protein metabolism.
Human beings are ureotelic animals. They excrete mainly urea eliminated by urine. Urea is the product of the degradation of amino acids.
Excretion of ammonia requires more water. So, it is mainly excreted by aquatic animals. Aquatic animals such as amoeba, sponges, hydra, star fish, bony fishes and tadpoles are ammonotelic
Excretion of uric acid requires the least amount of water. Birds, reptiles and some terrestrial invertebrates produce uric acid as waste in the form of white paste or powder.
Histidine is an amino acid. It is not a form of nitrogenous waste.