What process is responsible for breaking salt bonds in hair?

The correct answer is that a change in the hair's pH is responsible for breaking salt bonds in hair. Salt bonds are formed between the negatively charged side chains of amino acids, which can be affected by changes in the pH level. Altering the pH can lead to the formation or breaking of these ionic bonds, as the chemical environment changes, allowing for the restructuring of the hair.

In practice, when a chemical treatment is applied that alters the pH, it can have a direct impact on the stability of these salt bonds, leading to changes in the hair's texture and shape. This is particularly relevant in processes like relaxing or perming hair, where the breaking and reforming of bonds are essential for achieving the desired results.

Other choices do not directly break salt bonds in the same manner. Heat application can modify the shape of hair temporarily but does not consistently break the ionic bonds responsible for hair structure. Moisture absorption can enhance flexibility but does not primarily focus on breaking salt bonds. Likewise, while enzyme action can impact hair through various biochemical processes, it does not specifically target salt bonds in the same way that pH changes do.