Which statement best describes an ad impression?

The selected answer option, A single view of an ad by one individual, is correct because an ad impression refers to the moment when an ad is viewed by a user. It is counted each time the ad appears on a user's screen, regardless of whether the user interacts with it, such as clicking on the ad. This means that even if the user doesn't click on the ad, as long as it is displayed on their device, it counts as an impression. The other options, such as a user arriving on a landing page after clicking an ad or clicking on an ad, refer to other metrics like clicks or conversions, not impressions. A single web page load does not necessarily correspond to a single ad impression, as multiple ads may be loaded on a page. Therefore, an impression is best defined as the view of an ad by an individual.