What solution should be recommended to generate monthly reports of new Azure Resource Manager resource deployments?

The Azure Activity Log is the most appropriate solution for generating monthly reports of new Azure Resource Manager resource deployments. The Activity Log provides a comprehensive view of all activities within an Azure subscription, including the creation, modification, and deletion of resources. It records events related to resource deployments and allows users to filter logs by specific criteria, such as time range and resource type, making it easier to track changes over a given month.

Furthermore, the Activity Log can be used to generate insights into trends and usage of resources, which is particularly useful for reporting purposes. Users can export this data or integrate it with other Azure services, such as Azure Monitor or Azure Logic Apps, to automate the reporting process or generate detailed analyses.

While Azure Arc, Azure Analysis Services, and Azure Monitor action groups are powerful tools for various tasks in Azure, they do not specifically cater to the need for reporting on resource deployments in the way the Activity Log does. Azure Arc focuses on managing resources across on-premises, multi-cloud, and edge environments; Azure Analysis Services is used for analytical data modeling; and Azure Monitor action groups handle alerts and actions based on monitoring criteria but do not provide the detailed activity log necessary for tracking resource deployments effectively.