What is the primary function of conditioner in hair care?

The primary function of conditioner in hair care is to moisturize and detangle hair. Conditioners are formulated with ingredients that help to relax the hair's cuticle, making it smoother and more manageable. This not only enhances the hair's moisture content but also reduces friction among hair strands, thereby easing the detangling process. As a result, hair is more likely to be left soft and shiny, with less occurrence of breakage during styling or combing.

Moisturizing is crucial for maintaining the health of hair, especially if it is dry or damaged. Conditioners help restore the hair's natural oils, ensuring that it remains hydrated. By smoothing the surface of the hair, conditioners also contribute to a polished appearance and help to protect the hair from environmental stressors.

While other options address specific aspects of hair care, they do not capture the central role of a conditioner. Adding color, cleansing, or providing heat protection are important processes in hair care, but they serve different purposes and are typically addressed by other products, such as hair dyes, shampoos, or heat protectants, rather than conditioners. Thus, option C accurately highlights the main purpose of using conditioner in a hair care routine.