Which of the following can be modified using Shop API hooks in SFCC?

The correct choice is that address validation can be modified using Shop API hooks in Salesforce Commerce Cloud (SFCC). Shop API hooks are designed to enhance and customize various aspects of the shopping experience by allowing developers to intervene at specific points in the API’s flow.

Address validation is an essential feature during the checkout process, ensuring that customer addresses are accurate and formatted correctly. By utilizing the Shop API hooks, developers can implement custom validation logic or integrate third-party address validation services that ensure the addresses provided by customers are verified and fulfill the necessary criteria for successful order processing.

Other options include functionalities that either require different methods of modification or are outside the scope of Shop API hooks. For instance, order confirmation emails generally involve server-side customization, while discount coupons typically are managed through promotion engines or business logic, focusing on pricing and transactions rather than the core shopping API. User interface design, on the other hand, pertains more to frontend customizations and does not relate to the modifications available through Shop API hooks. Thus, address validation stands out as an appropriate choice for modification through these specific hooks.