What product is used to neutralize hair after a perm?

Neutralizer is the correct choice because it plays a vital role in the perming process. After the curls have been set using perm solution, the neutralizer is applied to reform the disulfide bonds in the hair, ensuring that the new curl pattern is locked in place. This step is crucial, as it stabilizes the hair structure and prevents the curls from falling out.

Shampoo is typically used for cleansing the hair, not for altering its structure. Conditioner may help with moisture and detangling hair, but it does not change the hair's chemical composition or lock in curls. Moisturizer is often used to hydrate hair but is not specifically designed to neutralize or set curls post-perm. Thus, the neutralizer is essential for achieving the desired long-lasting results after a perm treatment.