An organization must separate development and production workloads and manage billing independently. Which Azure concept supports this scenario?

Subscriptions are the correct answer because they provide a billing boundary and a management boundary for Azure resources. By creating separate subscriptions for development and production, an organization can manage costs independently for each environment and apply different policies or access controls. Resource groups are logical containers for related resources within a subscription, but they don't provide separate billing or independent management at the subscription level. Azure regions are geographical locations where Azure services are hosted, not a mechanism for billing separation. Tags are metadata labels used to organize and categorize resources, but they don't enforce billing or management boundaries.