Janice has set up a sponsored ad for her new series of cookbooks. She has selected the keyword "computer" for this ad. Which principle explains why her ad may not display?

Janice's ad may not display due to a lack of relevancy. Advertising platforms prioritize showing users ads that are highly pertinent to their search queries or browsing behavior. If Janice is selling cookbooks, the keyword "computer" is completely unrelated to her product. The ad system will likely determine that this keyword is not relevant to her ad content, leading to low ad quality scores, higher bids required to compete, or even preventing the ad from being shown at all. Cost-per-click (CPC) is a bidding model, not a reason for an ad not displaying due to keyword mismatch. Engagement refers to user interaction with an ad, which happens after display. Ad spend is the budget allocated, and while it can limit reach, it doesn't explain why a specific, irrelevant keyword prevents display.