In which of the following vertebrates does the skin function as a respiratory surface

In frogs, the skin functions as a respiratory surface. Frogs have moist, permeable skin that allows for gas exchange, meaning they can take in oxygen and release carbon dioxide through their skin. This is particularly important for frogs because they spend much of their time in water, where they are less able to obtain oxygen through their lungs. The skin on their underside is especially well adapted for this function and is often covered in tiny bumps, called papillae, which increase the surface area available for gas exchange. In contrast, rats, lizards, and fish do not use their skin as a respiratory surface. These animals have specialized respiratory systems, such as lungs or gills, that are specifically designed to exchange gases and support their respiratory needs.