Explanation

The dermis is the layer of skin beneath the epidermis, and it contains:

• Blood vessels (which supply oxygen and nutrients to the skin)
• Nerve endings (which transmit sensory information)
• Hair follicles (which produce hair)
• Sebaceous glands (which produce oil)
• Sweat glands (which produce sweat)
• Collagen and elastin fibers (which provide structure and elasticity)

A layer of dead cells is actually a characteristic of the epidermis, the outermost layer of skin, where dead skin cells are constantly shed and replaced by new ones.

So, the correct answer is A layer of dead cells!