For 18 months, Warner-Lambert Co. was required to include the following statement in all television advertisements for Listerine: "Listerine will not help prevent colds or sore throats or lessen their severity." This requirement was imposed by the FTC because previous advertising had caused consumers to believe Listerine was effective against colds. The new ad which included the statement described above is an example of corrective advertising persuasive advertising unethical advertising deceptive advertising follow-up advertising