Final answer:
The advertising company has used the technique of Testimonials to persuade you to get the product.
Step-by-step explanation:
The advertising company has used the technique of Testimonials to persuade you to get the product. Testimonials are statements or endorsements from individuals who have used the product and found it effective. In this case, the billboard claims that 85% of doctors use the product, suggesting that it is reliable and trustworthy.
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