What is hair primarily composed of?

Hair is primarily composed of keratins, which are a type of fibrous protein. Keratins provide structural strength and protect the cells from damage or stress. They play a crucial role in the composition of hair, as well as skin and nails, and are responsible for the distinct properties of hair, such as its durability and resistance to wear.

Collagen, while an important structural protein in connective tissues such as skin, cartilage, and bones, is not a component of hair itself. Elastin is another protein that provides elasticity to tissues, allowing them to resume their shape after stretching or contracting, but it is not found in hair. Melanin is a pigment responsible for the color of hair, skin, and eyes; however, it does not contribute to the structural composition of hair.

Thus, the composition of hair relies mainly on keratins, making it the correct answer.