Continuing cell division occurs in which of the following skin layers?

The stratum basale, which is the deepest layer of the epidermis, is responsible for the continuous division of cells. This layer contains basal cells that are actively undergoing mitosis to produce new keratinocytes, which migrate upward through the layers of the epidermis. As these cells proliferate in the stratum basale, they gradually replace the outer layers of skin cells that are shed through the natural process of exfoliation.

This continuous cell division is crucial for maintaining the skin's integrity, repairing injuries, and ensuring that there is a constant supply of new cells, which ultimately contributes to the regeneration of the epidermis. This layer is also vital for the overall health and resilience of the skin, as it contributes to the barrier function and plays a role in several skin processes.

The other choices do not represent layers or structures involved in ongoing cell division in the same way. The hypodermis is primarily composed of adipose tissue and connective tissue, while melanocytes are pigment-producing cells that are found in the stratum basale but do not divide continuously like the basal cells. The keratin layer refers to the outermost layer of dead keratinized cells and does not participate in cell division.