An advertiser is interested in driving return on ad spend (ROAS). Which optimization event is best suited for this goal?

The Checkout optimization event is best suited for driving Return on Ad Spend (ROAS) because it directly tracks and optimizes for completed purchases, which are the ultimate measure of revenue generated from advertising. By optimizing for Checkout, Pinterest's algorithm will prioritize showing ads to users most likely to complete a purchase, thereby maximizing the advertiser's return on investment. Pin engagement, page visits, and outbound clicks are earlier-stage engagement metrics that indicate interest but do not directly translate to revenue, making them less effective for a ROAS-focused goal.