Option (4) is the correct answer because birds (Pavo) excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water. Option (3) and (2) are incorrect because many bony fishes (like Hippocampus) and aquatic amphibians (like Salamandra) are ammonotelic in nature. Option (1) is incorrect because mammals (like Ornithorhynchus) mainly excrete urea and are called ureotelic animals.