Which part of the hair provides strength, elasticity, and natural color?

The cortex is the primary part of the hair that contributes to strength, elasticity, and natural color. Comprising about 80% of the hair's overall structure, the cortex contains keratin, a fibrous protein that provides the hair with its strength and resilience. Additionally, the cortex houses melanin, the pigment responsible for the hair's natural color. This layer's composition and structure are crucial for how hair behaves, including its ability to stretch and retain shape, characteristics that are important for styling and overall hair health.

The other parts, while they play distinct roles, do not primarily contribute to these specific attributes. The cuticle serves as the protective outer layer but does not influence strength or elasticity significantly. The medulla, found in some hair types, is a central core but plays a lesser role in the strength and color of the hair. The hair root, located below the skin's surface, is vital for hair growth and anchoring, but it doesn’t directly contribute to the physical properties of the hair shaft itself. Hence, the cortex is the correct choice when discussing the attributes of strength, elasticity, and color in hair.