Which ingredient found in some mouthwashes is most commonly associated with causing extrinsic staining of teeth?

Cetylpyridinium chloride (CPC) is a quaternary ammonium antiseptic used in mouthwashes that is associated with extrinsic tooth staining, though the staining is generally less severe than that caused by chlorhexidine. CPC causes brown extrinsic staining through interaction with dietary chromogens. Note: Chlorhexidine is the antiseptic most strongly associated with tooth staining, but among the options given in this question, CPC is correct. Sodium lauryl sulfate is a detergent/surfactant. Sodium fluoride and alcohol do not typically cause significant tooth staining.