With pay-per-click search advertising, when are you charged?
Each time your ad is displayed on the search results page.
Each time a customer makes a purchase from your website.
When your ad goes live.
Each time a customer clicks your ad.
Each time a customer clicks your ad you were charged with pay-per-click search advertising.
This question is a part of Microsoft Advertising Certified Professional Exam. You can read all the right answers here : Bing Ads Accreditation Exam Answers