Final answer:
Nutrients and oxygen are supplied to the skin by the blood through the blood vessels in the dermis layer of the skin.
Step-by-step explanation:
Nutrients and oxygen are supplied to the skin primarily by the blood circulation system. The skin consists of two main layers, the epidermis, which is the outermost layer, and the dermis, which is found beneath it and contains connective tissues, hair follicles, oil glands, sweat glands, and blood vessels.
It is through the blood vessels in the dermis that nutrients and oxygen are delivered to the skin. These blood vessels are a part of the body's circulatory system, which transports nutrients and oxygen to all cells of the body, including those of the skin.
Lymph is not primarily responsible for delivering nutrients and oxygen to the skin; instead, it's involved in the immune response and the transport of lymphatic fluid. Skin conditions such as pustules and papules (types of skin lesions) are not related to the supply of nutrients and oxygen; rather, they are associated with inflammation or infections of the skin. Therefore, the correct answer to the question is a. blood.