Final answer:
A color-safe conditioner is designed to close the cuticle after a color service, which helps to prevent the color from fading, unlike other types of conditioners that focus on different hair needs.
Step-by-step explanation:
The type of conditioner that is formulated to close the cuticle after a color service and help prevent color from fading is a color-safe conditioner. After the hair is colored, the cuticle layer of the hair is opened to allow color to penetrate the hair shaft. Once the color process is completed, it's important to close that cuticle to seal in the color and prevent rapid fading. A color-safe conditioner is specifically designed to do this without stripping the color, as it has a low pH level that helps to close the cuticle and lock in the dye. In comparison, leave-in conditioners, deep conditioners, and protein conditioners serve different purposes such as hydration, repair, and strengthening but might not necessarily address color retention as effectively as color-safe conditioners.