The waste product of reptiles, birds, and insects is:

Explanation

The correct answer is uric acid, as it is the primary nitrogenous waste product excreted by reptiles, birds, and insects. Uric acid is advantageous in these animals because it is relatively non-toxic and requires minimal water for excretion, which is crucial for survival in environments where water conservation is necessary. Ammonia is highly toxic and requires a lot of water to be safely excreted, which is why it is more commonly excreted by aquatic animals. Urea, while less toxic than ammonia, still requires more water for excretion than uric acid, making it more common in mammals and some amphibians.