[Reference:, https://docs.microsoft.com/en-us/azure/dms/dms-overview, , , , , , , Basic Concept: This question tests choosing the correct Azure migration approach by matching the source platform, target service, downtime tolerance, and administrative effort., Why C is Correct: Azure Database Migration Service is the managed migration service used to move database engines to Azure targets with online or offline migration modes depending on source and target support. The scenario asks for: What should you use to migrate the PostgreSQL database? That makes Azure Database Migration Service the option that satisfies the required Azure SQL layer and operational outcome., Why A is Wrong: Azure Data Box is an Azure data-platform feature, but it must match the workload model, service tier, migration path, or deployment constraint described in the scenario. It would solve a neighboring problem, but not the deployment, sizing, or migration requirement in this item., Why B is Wrong: AzCopy is an Azure data-platform feature, but it must match the workload model, service tier, migration path, or deployment constraint described in the scenario. It mismatches the target platform, migration method, compute tier, or deployment model described in the scenario, so it would not satisfy the workload as stated., Why D is Wrong: Azure Site Recovery is an Azure data-platform feature, but it must match the workload model, service tier, migration path, or deployment constraint described in the scenario. It would solve a neighboring problem, but not the deployment, sizing, or migration requirement in this item., ]