South Carolina Barber Practice Exam

Hair is composed of keratin, which is a type of protein found in our skin, hair, and nails. While options A, B, and D may all be present in the human body, they are not the main components of hair. Hemoglobin is found in red blood cells and is responsible for transporting oxygen throughout the body. Melanin is a pigment that gives skin and hair its color. Calcium is a mineral that helps with bone health and muscle function, but is not a major component of hair. Therefore, the correct answer is keratin.