Why do advertisers use testimonials?

a.) they provide accurate, proven information to inform the consumer.
b.) they provide hidden lies that will always misinform the consumer.
c.) they provide celebrity encouragement to persuade the consumer.
d.) they provide rebate money after purchases to refund the consumer.

Advertisers use testimonials because: A) They provide accurate, proven information to inform the customer.

If others have used a product and have had success with it, their testimony provides assurance that the product is valuable and does what it is advertised to do. Of course, this assumes that those providing the testimonials are being honest and accurate in the information they give. In recent history, we have seen the use of the Internet to enhance a product's reputation with all sorts of glowing online reviews ... but with many of those reviews coming from persons paid by the merchants to post positive testimonials without even using the product.