Corey is analyzing an advertisement that indicates that the majority of the population uses a specific brand of sunscreen. Which persuasive technique is being used?

The persuasive technique wherein Corey is analyzing an advertisement that indicates that the majority of the population uses a specific brand of sunscreen is called the bandwagon effect. This technique employs the use of other people or the majority in order to persuade the buyer to 'hop in the bandwagon' and use the product too.