The deepest and most active division of skin is called the dermis.

Here's why:

* Dermis: This layer is responsible for the skin's strength, elasticity, and overall health. It contains:

* Collagen and elastin fibers: These provide structure and support.

* Blood vessels: Deliver nutrients and remove waste products.

* Nerves: Provide sensation.

* Hair follicles: Produce hair.

* Sweat glands: Regulate body temperature.

* Sebaceous glands: Produce oil to lubricate the skin.

* Epidermis: The outer layer of skin, primarily responsible for protection from the environment. While it contains some cells that divide, it's not as metabolically active as the dermis.

Let me know if you have any other questions!