Final answer:
Toning colors are used in hair coloring to adjust the final shade of prelightened hair, providing warmness or coolness as desired. They are distinct from art pastels but leverage the same principles of subtle pigment application.
Step-by-step explanation:
The correct answer to the student's question is B) Toning colors. Toning colors are used in hair coloring to add subtle nuances, often to pre-lightened hair, in order to achieve the desired shade, impart a particular tone, or neutralize unwanted undertones. Hair toners come after the initial bleaching or lightening to refine the hair color. Unlike pastels in art, which are a form of medium made from powdered pigments and a binder, toning colors in hair care are specifically developed with color theory in mind to adjust hair color. The pigment in these toners is designed not to overwhelm the hair color but to enhance or soften it into the desired shade.