Which Azure service should you use to generate a monthly report of all new Azure Resource Manager (ARM) resource deployments in a subscription?

Azure Log Analytics is the correct choice because it's a service within Azure Monitor that allows you to collect, query, and analyze log data from various Azure resources. You can configure diagnostic settings for your subscriptions to send Azure Activity Log data, which includes resource deployment events, to a Log Analytics workspace. From there, you can write Kusto Query Language (KQL) queries to filter for new ARM deployments within a specified timeframe and then export or visualize this data for monthly reporting. Application Insights is primarily for monitoring application performance and usage, not infrastructure deployments. Azure Arc extends Azure management to on-premises and other cloud environments, but it doesn't inherently provide reporting on Azure resource deployments. Azure Monitor metrics focuses on numerical time-series data, which is less suitable for detailed event-based reporting like new resource deployments compared to the rich log data available in Log Analytics.