Which hair treatment technique is primarily used to create curls or waves?

Perming is the correct answer because this hair treatment technique is specifically designed to create curls or waves in the hair. The perming process involves the use of chemical solutions that alter the structure of the hair, allowing it to form into the desired curly or wavy shape. The technique typically involves wrapping sections of hair around rods or rollers, applying a perm solution, and then neutralizing the hair to set the curls or waves.

While hair straightening is a technique aimed at achieving a smooth and sleek look, blow drying is primarily a method of drying hair and can also add volume or smoothness, but does not inherently create curls. Layer cutting refers to a haircutting technique that adds dimension and shape to the hairstyle but does not create curls or waves.