What is the primary effect of a permanent wave on hair?

The primary effect of a permanent wave on hair is to change the hair's structure and create curls. This process involves breaking and reforming the bonds within the hair's keratin structure using a chemical solution, which allows for the formation of curls or waves that are set to last for an extended period of time.

The chemical reaction alters the natural shape of the hair, enabling it to adopt new patterns that can range from soft waves to tight curls, depending on the technique and products used. The intended outcome is to provide clients with a lasting hairstyle that offers volume and texture, which contributes to the versatility in hairstyling.

Other options offered do not pertain to the primary purpose of a permanent wave. While lightening hair color, removing split ends, and straightening hair are significant aspects of hair treatment, they do not relate to the process or goals of obtaining curls through a permanent wave, thereby distinguishing the primary effect as a structural transformation aimed at creating lasting curls or waves.