A local product inventory feed mandates the “store code” attribute.

• item_code
• product_type
• location ID
• store code

The correct answer is: store code

Explanation: Within a local product inventory feed, the “store code” attribute is indispensable. Presented as [store_code], it’s crucial to note that this attribute is case-sensitive and should be consistent with the store codes provided in your Business Profiles. Additionally, for those utilizing the merchant-hosted local storefront (full) feature, the “price” attribute needs to be part of your feed. This price should be an exact representation of what’s displayed on your landing page.

Read more here: https://support.google.com/merchants/answer/3061342