Which of the following is classified as an unregulated service?

Ear piercing is classified as an unregulated service because it does not typically require a license or specialized training in the way that hair coloring, shampooing, and hair cutting do in a salon environment. In many states, ear piercing can be performed by individuals with minimal training, often in retail or non-specialized settings, because it is considered a straightforward procedure that does not involve the same health and safety considerations that other salon services entail.

In comparison, hair coloring, shampooing, and hair cutting are regulated services, meaning that they require practitioners to obtain specific licenses and adhere to health and safety regulations set forth by state boards of cosmetology. These regulations help ensure that clients receive safe and professional care during these services, which involve chemical applications or close contact with the client's skin and hair.