Which of the following services requires the use of a patch test?

Hair coloring requires the use of a patch test to determine if an individual has any allergic reactions to the hair dye or its ingredients. A patch test is a precautionary measure that involves applying a small amount of the hair color on a discreet area of the skin, typically behind the ear or on the inner arm, and waiting for 24 to 48 hours to see if any irritation, redness, or allergic reaction occurs. This is critical because some hair coloring products contain strong chemicals that may cause adverse reactions in sensitive individuals. Conducting a patch test ensures the safety and well-being of the client before applying color to the entire head.

In contrast, services like shampooing hair, hair trimming, and blow drying do not involve chemicals that could trigger an allergic reaction, thus they do not necessitate a patch test.