D)Mucous glands because mammals doesn't contain mucous gland in skin but they consist them in "digestive tract"

Frogs skin vs Mammalian skin

Introduction:
Frogs and mammals have different types of skin adaptations to suit their respective environments. While mammalian skin is specialized for various functions, such as protection, thermoregulation, and sensory perception, frog skin has unique characteristics that allow it to thrive in its aquatic and terrestrial habitats.

Mucous Glands in Frog Skin:
One key difference between frog skin and mammalian skin is the presence of mucous glands in frogs. These mucous glands secrete a slimy substance called mucus, which covers the frog's skin. Mucus helps to keep the frog's skin moist, which is crucial for respiration through the skin. Frogs can absorb oxygen through their skin, and the moist environment provided by the mucus aids in this process. Additionally, the mucus layer helps protect the frog's skin from drying out and provides a slippery surface, making it easier for the frog to move in its habitat.

Sebaceous Glands:
Sebaceous glands, which are present in mammalian skin, are absent in frog skin. Sebaceous glands produce sebum, an oily substance that helps lubricate and waterproof the mammalian skin. Sebum also plays a role in maintaining the skin's pH balance and providing some protection against bacterial and fungal infections. However, since frogs have a moist environment due to the presence of mucous glands, sebaceous glands are not necessary for their skin.

Stratum Germinativum:
The stratum germinativum is the basal layer of the epidermis in mammalian skin. It is responsible for the production of new skin cells, which then migrate upwards to replace the older cells. In frog skin, the stratum germinativum is absent. Instead, frogs have a unique skin structure called the Malpighian layer.

Malpighian Layer:
The Malpighian layer is a specialized layer in frog skin that lies beneath the outermost layer called the epidermis. It is responsible for the production of new skin cells and pigment cells. The Malpighian layer also contains melanophores, which are responsible for the coloration and camouflage of frogs. This layer is well adapted to the frog's environment and plays a vital role in their survival.

Conclusion:
In conclusion, while mammalian skin has sebaceous glands and a stratum germinativum, frog skin lacks these features. Instead, frog skin has mucous glands that secrete mucus to keep the skin moist and protect it from drying out. The frog's skin also has a specialized layer called the Malpighian layer, which is responsible for the production of new skin cells and pigment cells. These unique adaptations in frog skin allow them to thrive in their aquatic and terrestrial habitats.