Skin cells can have terminally differentiated. They undergo differentiation to become specialized cells that perform specific functions, such as forming the protective outer layer of the skin. Skin cells can also become senescent quickly, especially in response to damage or stress. However, they are not considered stem cells, as they do not have the capability for self-renewal and differentiation into multiple cell types.
Therefore, the most accurate response regarding skin cells in this context would be that they have terminally differentiated.