Which of the following describes the function of bleach in hair treatment?

The correct choice accurately describes the primary function of bleach in hair treatment by emphasizing its role in altering the hair's natural pigment. Bleach works by breaking down the melanin in the hair, which is responsible for the natural color. This process involves chemical reactions that ultimately disperse and dissolve the pigment molecules, leading to a lightening effect. As a result, bleach can lighten hair to various degrees depending on the strength of the bleach used and the application technique.

This understanding is crucial for stylists, as it lays the foundation for their work in color treatments and helps them achieve desired looks while being mindful of the hair's integrity during the bleaching process.