Which service should a DevOps team configure to send proactive alerts when a specific web app becomes unavailable?

Azure Monitor is the correct choice because it provides comprehensive monitoring of Azure resources, including web apps. It can collect metrics and logs, and crucially, allows you to configure alert rules based on specific conditions, such as a web app's availability status. When the condition is met (e.g., the web app becomes unavailable), Azure Monitor can trigger proactive notifications to the DevOps team. Azure Advisor provides recommendations for optimizing Azure resources, but it doesn't offer real-time alerting for service unavailability. Azure Resource Health informs you about the health of your individual resources and provides troubleshooting guidance, but Azure Monitor is used to configure proactive alerts. Azure Policy helps enforce organizational standards and compliance, not for real-time operational alerting.