Which reducing agent is commonly used in thio relaxers, which are milder than hydroxide-based relaxers?
a.Sodium hydroxide
b.Guanidine hydroxide
c.Hydrogen peroxide
d.Ammonium thioglycolate
Explanation
Ammonium thioglycolate (thio) breaks disulfide bonds via reduction rather than the higher-pH hydroxide cleavage. Thio relaxers are milder and often used on previously color-treated or finer hair. Hydroxide relaxers (sodium, guanidine) are stronger and work by lanthionization.
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