Temporary hair color only causes what type of change?

Temporary hair color causes a physical change in the hair. This type of change refers to alterations that do not create new substances; rather, they modify the appearance of the hair without changing its chemical structure. Temporary hair color coats the outer layer of the hair shaft, allowing it to be easily washed out with shampoo, which is a key characteristic of physical changes.

In contrast, chemical changes involve a transformation that alters the chemical composition of the product or material, such as the process involved with permanent hair dyes that penetrate the hair shaft and result in a lasting color change. Permanent changes, as indicated by another option, result in a lasting change that cannot be easily reversed. Oxidative processes, typical in certain types of hair coloring, cause a reaction that leads to structural changes in the hair. None of these applies to temporary hair color, further confirming that it purely results in a physical change.