To disable the "Discover" credit card type for all checkouts in Salesforce B2C Commerce, the developer should:
* B. Credit card exclusion rules in the Merchant Tools > Site Preferences > Payment Preferences module.In the Business Manager, the Payment Preferences module under Site Preferences allows administrators to configure which credit cards are accepted by setting credit card exclusion rules. This module provides a user interface where specific credit card types, such as "Discover", can be enabled or disabled across the site. This is the correct approach to centrally manage payment options without requiring code changes.