Which attribute is optional in a product feed for Google Merchant Center?

In a product feed for Google Merchant Center, the product_type attribute is considered optional, which makes it the correct choice. The product_type attribute allows merchants to categorize their products based on their own taxonomy, helping with organization and ad targeting. While this attribute can enhance the visibility of a product and assist in reporting and analysis, it is not mandatory for the product feed to be processed successfully by Google Merchant Center.

In contrast, attributes like image_link, availability, and price are essential. The image_link provides the necessary visual representation of the product, availability informs potential buyers whether the product is in stock, and price is critical for buyers to determine the cost of the product. These essential attributes ensure that customers receive complete and accurate information about the products, which is fundamental for successful advertising in the shopping ads ecosystem.