Which of the following practices is included in body art?

Body piercing is included in body art because it involves the intentional creation of a hole or puncture in the body, typically for the insertion of jewelry. This practice is a form of body modification that has cultural, aesthetic, or personal significance for many individuals. Body art encompasses various practices that alter the way the body looks, and body piercing is a prominent example due to its lasting physical alteration and artistic expression.

In contrast, the other practices listed—massage therapy, hair styling, and facial treatments—do not fit the definition of body art as they do not involve modifications to the body itself. Massage therapy is focused on relaxation and therapeutic benefits, hair styling revolves around grooming and managing hair, and facial treatments are primarily aimed at skin care and aesthetics without altering the physical structure of the body. Thus, body piercing stands out as the correct answer due to its unique focus on altering the body's appearance through intentional physical modification.