The correct answer is option 2 - Birds. Uric acid is the chief nitrogenous waste in birds. Nitrogenous waste is produced as a result of the breakdown of proteins in the body. Different animals excrete different types of nitrogenous waste depending on their evolutionary adaptations. Uric acid is unique because it is relatively insoluble in water, allowing birds to excrete it as a semi-solid or paste-like substance. This is beneficial for birds as it helps minimize water loss. Frogs, on the other hand, excrete nitrogenous waste in the form of urea, which is more soluble in water. Fish excrete nitrogenous waste as ammonia, which is highly soluble and toxic. While uric acid is not the chief nitrogenous waste in frogs, fishes, or mankind, it is the primary nitrogenous waste in birds.