Maine Barber Practice Exam

The patch test is not used to determine hair color levels, as that can be assessed through other means such as a color consultation with a stylist. It is also not used to measure the percentage of body water, as that can be measured through other methods like a body composition analysis. Lastly, the patch test is not used to assess familiarity with a product or service, as it is specifically designed to determine if a person may have a sensitivity to aniline derivatives. These are chemicals commonly found in hair dyes and other products. Therefore, option B is the correct answer as it provides an accurate explanation of the purpose of a patch test.