Azure Policy is the primary Azure service for implementing governance and ensuring compliance. It allows you to create, assign, and manage policies that enforce rules over your resources. The Microsoft cloud security benchmark (MCSB) is available as a built-in policy initiative within Azure Policy. By assigning this initiative to the relevant scope (e.g., the subscription or resource groups where App Services are deployed), you can continuously audit the configuration of the deployed apps against MCSB recommendations. Azure Policy can also be set to "Deny" non-compliant deployments, ensuring that any app deployed through Azure DevOps or any other method must adhere to the benchmark to be created or updated.

A. DevOps security in Microsoft Defender for Cloud: This provides security posture visibility and threat detection within the DevOps pipeline and code, not for enforcing compliance on deployed Azure resources.
B. Microsoft Defender for App Service: This is a threat detection service that identifies attacks against running applications; it does not enforce configuration compliance against a benchmark.
C. a branch policy in Azure DevOps: This enforces rules on the source code repository and pull request process, not on the configuration of the final deployed Azure resources.

1. Azure Policy and MCSB: Microsoft Learn, "Overview of the Microsoft cloud security benchmark (v1)". Under the "Monitor compliance" section, it states, "You can monitor your compliance with this benchmark by using the Microsoft cloud security benchmark initiative in Azure Policy."

2. Azure Policy for Governance: Microsoft Learn, "What is Azure Policy?". The introduction states, "Azure Policy is a service in Azure that you use to create, assign, and manage policies. These policies enforce different rules and effects over your resources, so those resources stay compliant with your corporate standards and service level agreements."

3. DevOps Security in Defender for Cloud: Microsoft Learn, "DevOps security". The overview explains, "The DevOps security workload in Defender for Cloud unifies security management... to provide full visibility into your application development lifecycle and security posture from code to cloud." This highlights its focus on the pipeline, not the deployed resource's compliance state.

4. Microsoft Defender for App Service: Microsoft Learn, "Protect your Azure App Service web apps and APIs". The documentation states, "Microsoft Defender for App Service uses the scale of the cloud to identify attacks targeting applications running over App Service." This confirms its role in threat detection, not configuration compliance.