A firm must keep customer data within specific countries to meet regulations. Which Azure capability enforces this?

Region selection is the correct answer because Azure regions are geographically distinct data centers that adhere to specific data residency and compliance requirements. By choosing a particular region, a firm ensures its customer data remains within the geographical boundaries mandated by regulations. Content Delivery Network (CDN) is incorrect because it's used for caching content closer to users for faster delivery, not for enforcing data residency. Edge zones are extensions of Azure regions that bring services closer to users, but the primary control for data residency at a country level is the region itself. Azure Lighthouse is incorrect because it allows for delegated management of Azure resources across multiple tenants, not for data residency enforcement.