Option A refers to PolarDB Global Database Network (GDN), Alibaba Cloud ' s architecture for connecting PolarDB clusters across regions. A GDN contains a primary cluster and secondary regional clusters. Data changes are continuously replicated, local reads can be served by regional clusters, and write operations are routed to the primary cluster. Maintaining a single authoritative write path is particularly important for reservation transactions where concurrent booking operations must be controlled consistently.

Option C provides resilient application capacity by deploying ECS application servers in multiple regions and using ALB within each regional deployment to distribute requests among healthy instances. In a complete production implementation, a global routing mechanism such as DNS traffic management or Global Accelerator would normally direct users between those regional application stacks.

Function Compute is suitable for payment-gateway integrations because payment callbacks and API interactions are event-driven or request-driven workloads. Function Compute can be exposed securely through API Gateway, which provides routing, authentication, traffic control, and API management without persistent integration servers.

OSS versioning is useful for protecting stored objects but does not supply the transactional database, regional application availability, or payment-processing functionality required here.

Study Guide reference: Building Highly Available, Performant Cloud Architecture — multi-region PolarDB, GDN, regional application tiers, ALB, and serverless integration.

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