Which of the following techniques is used for applying hair dye?

The technique of sectioning and applying with a brush is the most effective method for applying hair dye. This approach allows for precise control over the application process, ensuring that the dye is distributed evenly throughout the hair. By sectioning the hair, the stylist can work through smaller portions, which helps in applying the color thoroughly and minimizes the risk of missing spots or creating uneven tones. Using a brush allows for accurate placement of the dye along the hair strands, which is particularly important for achieving a uniform result, especially with more intricate techniques such as highlights or balayage.

Other methods such as combing, rubbing in with hands, or continuous spraying may not provide the precision needed for even color application. Combing alone may move the color but does not apply it effectively. Rubbing in with hands can lead to streaks and an uneven application, and spraying continuously may result in a mist that does not cover the hair adequately. Therefore, sectioning and applying with a brush stands out as the best technique for achieving a professional and polished look when dyeing hair.