D. Stratum Corneum
The layer of the epidermis that contains flat, dead cells filled with keratin and surrounded by lipids is (d) Stratum Corneum. This layer is the outermost layer of the epidermis and serves as a protective barrier for the skin, preventing the loss of water and protecting against external pathogens and environmental factors. The accumulation of keratin and lipids in the stratum corneum gives it its characteristic properties.