The correct option is D Keratin
Dermis is the inner thick layer of connective tissue, made of elastic fibres. It contains blood vessels, nerve fibres, hair follicles, etc. On the other hand, stratum corneum, the outermost layer of the epidermis consists of several layers of flat dead cells. These cells are made up of keratin protein. Keratin is also found in hairs, hoofs, nails, horns and silks.