John is running a test campaign with CTR as the main KPI. He is trafficking five ads per placement and wants to make sure the best performing ads are displayed more often to end users. Which setup is best suitable to John's goal?

The best setup is to create a delivery group with five ads and select "automatic optimization based on CTR" as the rotation method. This directly addresses John's goal of having the best-performing ads (based on CTR) displayed more often without manual intervention. The system will automatically adjust ad serving frequency based on their real-time CTR performance. Monitoring data and creative refresh is a reactive strategy; it doesn't automatically optimize delivery. Manually increasing delivery group weights is labor-intensive and doesn't provide real-time, dynamic optimization. Adding five delivery groups and detaching underperforming ones is overly complex and also requires manual intervention, defeating the purpose of automatic optimization.