Correct Answers: A
The Stackdriver Monitoring agent is a collectd-based daemon that gathers system and application metrics from virtual machine instances and sends them to Monitoring.
Metrics help understand how applications and system services are performing.
Stackdriver can monitor GCP, AWS, and third-party software.
Standard Stackdriver Monitoring can access some instance metrics, but using the Monitoring agent (optional ) you can define and gather all the data you need.
By default, the Monitoring agent collects disk, CPU, network, and process metrics. You can configure the Monitoring agent also to monitor third-party applications.
Cloud Armor is wrong because it is a service against denial of service and web attacks.