Explanation
To track shoe designs by products, prevent them from being deleted, and allow multiple designs for one product across various stages, the administrator should create a custom object for shoe designs and configure a custom lookup field for shoe designs on the Product object. This will create a one-to-many relationship between products and shoe designs, and allow users to link multiple shoe designs to one product record. To prevent shoe designs from being deleted, the administrator can use validation rules or permissions. Adding a custom master-detail field for shoe designs on the Product object will create a many-to-one relationship, which is not desired. Using the standard object for designs or configuring a validation rule will not meet the requirement. References:
https://help.salesforce.com/s/articleView?id=sf.customize_object_relationships_overview.htm&type=5