The shell of the egg is leathery in appearance in which of the following?:

Explanation

Reptile eggs, including those of snakes and many turtles, are characterized by their leathery shells, which are flexible and often adhere to one another. This adaptation helps protect the eggs in a terrestrial environment. In contrast, amphibians lay eggs in water with jelly-like coverings, birds have hard shells made of calcium carbonate, and most mammals do not lay eggs at all, with the exception of monotremes like the platypus, which do have leathery eggs but are a rare subgroup. Thus, the correct answer is reptiles.