Final answer:
The stratum corneum is not part of the integumentary system.
Step-by-step explanation:
The integumentary system is the organ system that protects the body from various kinds of damage, such as loss of water or abrasion from the outside. It comprises the skin and its appendages, including hair, nails, and various glands.
The integumentary system consists of the skin, hair, and nails. The hypodermis, sebaceous glands, and finger nails are all part of the integumentary system. Therefore, the correct answer is D. the stratum corneum, which is a layer of dead skin cells and not an actual organ or structure within the system.