You manage a business-critical backend application running on a Compute Engine managed instance group (MIG).

The correct answer is C because Cloud Monitoring already collects Compute Engine CPU utilization metrics and supports alerting policies with thresholds and duration windows. The requirement is to notify the operations team when average CPU utilization exceeds 75% for five continuous minutes, which maps directly to a Cloud Monitoring metric-based alert policy. Logs-based metrics are unnecessary because CPU utilization is not primarily a log event and is already available as a platform metric. Installing agents and writing custom polling scripts adds operational overhead and is less scalable. Autoscaling policies adjust capacity, but they do not replace alerting policies and do not provide the requested notification workflow by themselves. Cloud Monitoring is the native, low-maintenance solution.