To accommodate the requirement of changing the address form for a U.S.-based site from a Canadian configuration, the appropriate setup is option D: Create a new sub-folder in the forms folder named en_US and copy the existing address.xml file into this new folder. This method is consistent with Salesforce B2C Commerce best practices for managing site-specific customizations and localizations. This structure allows the system to easily identify and apply the correct localization settings based on the site context, enabling the U.S.
site to use a specific form configuration that differs from the Canadian version by providing the correct two-letter state abbreviations in the <options> list.