Because thedw.order.calculateTaxhook is alreadydefined and registered byapp_storefront_base, the custom controller does not need to register that implementation again. Its responsibility is to invoke the existing extension point throughdw.system.HookMgr.callHook(). Therefore, option A expresses the correct architectural pattern.

Salesforce ' s SFRA hook documentation separateshook registrationfromhook invocation. A cartridge that provides an implementation registers its hooks through its hook configuration, while consuming code calls the registered extension point withHookMgr.callHook(). B2C Commerce then resolves registered hook implementations from cartridges on the active cartridge path.

The current SFRA implementation itself invokes the tax extension point withHookMgr.callHook( ' dw.order.calculateTax ' , ' calculateTax ' , basket), demonstrating that calling code does not re-register the existing hook.

Accordingly, adding another hook location to the custom cartridge ' shooks.jsonorpackage.jsonmerely to call an already registered implementation is unnecessary. Registration is required for the cartridge implementing the hook, not every caller.

Study Guide reference:Application Development — hooks, HookMgr, extension-point registration, SFRA tax calculation, and cartridge extensibility.

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