How do Smart Shopping campaigns use machine learning to show a variety of the most relevant ads across Google networks to potential customers?

Questions: How do Smart Shopping campaigns use machine learning to show a variety of the most relevant ads across Google networks to potential customers?

Answer:

• By testing different combinations of text and images
• By making suggestions for image styles
• By testing different font styles for specific product types
• By understanding all site visitors through demographic data

This question is from Google Shopping Certification test.