As a cloud administrator for a global retail company, you are tasked with implementing a comprehensive monitoring solution that not only tracks the performance and health of Azure resources but also proactively notifies your team of critical conditions. The solution must support the creation of alert rules based on a wide range of signals, including metrics, logs, and activity logs. It should allow for the customization of alert severity levels to prioritize notifications and enable alerts to be sent through multiple channels such as email, SMS, and webhooks. Furthermore, the solution should seamlessly integrate with other Azure services to provide a unified monitoring experience. Given these requirements, which Azure Monitor feature would you use to achieve these objectives? (Choose one option.)