Illinois Cosmetology Practice Exam

Collagen is the major protein found in the dermis layer of the skin because it provides strength and structure to the skin. Option A, elastin, is also found in the dermis layer but it provides elasticity rather than strength. Option B, sebum, is a lubricant produced by the sebaceous glands in the skin but it is not a protein. Option D, melanin, is a pigment responsible for skin color and protection against UV radiation, but it is not a protein found in the dermis layer.