Which of the following is NOT one of the five main types of advertising?

The classification of advertising techniques typically includes methods that engage the audience through various persuasive strategies. Among these, "Plain Folks," "Testimonials," and "Scientific Evidence" are recognized as legitimate advertising types that utilize relatability, endorsements from satisfied users, and empirical data respectively to persuade consumers.

Plain Folks appeals to the audience by presenting products as relatable and endorsed by common people. This method works under the premise that consumers appreciate products that are seen as friendly and accessible.

Testimonials involve using endorsements from individuals, especially those who have had positive experiences with the product or service. This method builds trust and credibility by showcasing real experiences that potential customers can relate to.

Scientific Evidence utilizes research and empirical data to substantiate claims made in advertisements, which can enhance the perceived reliability and efficacy of a product or service in the eyes of the consumer.

On the other hand, the term "Appeal to Authority" does not specifically fit into the commonly recognized types of advertising. While authorities might endorse products, this strategy is not classified as a primary advertising type in the same way as the others listed. Instead, it serves as a logical fallacy in arguments rather than a standalone advertising method, thus making it the correct choice as it is not one of the five main types of advertising.