Final answer:
The characteristics of internal fertilization, leathery amniotic egg, and skin that resists drying are indicative of b. nonbird reptiles. These adaptations allow them to live on land without depending on a moist environment for the eggs or skin, distinguishing them from birds, chondrichthyans, mammals, and amphibians.
Step-by-step explanation:
Internal fertilization, leathery amniotic egg, and skin that resists drying are characteristics most closely associated with b. nonbird reptiles. These features are key adaptations for life on land. Nonbird reptiles are part of the amniotes, which includes reptiles, birds, and mammals.
However, the presence of leathery eggs and skin that resists desiccation without relying on moist environments distinctly points to nonbird reptiles. Birds do have amniotic eggs, but their shells are hard and made of calcium carbonate.
Chondrichthyans, such as sharks and rays, have internal fertilization but do not produce amniotic eggs. Mammals also have internal fertilization but most do not lay eggs with the exception of the monotremes (like echidnas and platypuses). Lastly, amphibians typically have external fertilization and produce eggs that do not have a shell, needing moist environments to survive.