Which hair color technique involves applying color to selected strands?

The technique that involves applying color to selected strands is highlights. This process typically focuses on lightening certain sections of the hair to create contrast against the base color, resulting in a multi-dimensional look. Highlights can be subtly blended for a natural effect or used dramatically for a more striking appearance. They enhance the overall hairstyle by adding depth and dimension.

Solid color involves applying a uniform color all over the hair, which does not focus on selected strands, while ombre is a specific gradient coloring technique where the hair is darker at the roots and gradually lightens towards the ends. Single process refers to applying a single color throughout the hair in one step, rather than focusing on select strands. Thus, highlights are specifically designed to enhance chosen areas, making them the correct answer.