How would you accurately describe the function of product groups in a Shopping campaign?

The correct answer is:

• Product groups are keywords that are defined by categories you can select in each of your campaigns.
• Product groups are remarketing lists that you want to advertise in each of your campaigns.
• Product groups are predefined themes that you can select in each of your campaigns.
• Product groups are used to specify which products from your feed you want to advertise in each campaign.