Answer: Client-side instrumentation implemented directly within the code., A synthetic client that periodically sends simulated user requests.

**Client-side instrumentation implemented directly within the code (Correct)**: This method allows you to measure service availability and performance from the user's perspective, capturing issues like load balancer misconfigurations or CDN failures that server-side metrics might miss. **A synthetic client that periodically sends simulated user requests (Correct)**: Synthetic monitoring mimics real user behavior to test service availability and performance, helping identify issues without relying on actual user traffic. **The logs generated by your application servers (Incorrect)**: While useful for diagnosing application issues, server logs may not reveal problems occurring outside the application, such as CDN failures. **The metrics that are extracted from the application servers (Incorrect)**: Similar to logs, server metrics provide valuable insights into application performance but may not detect external issues. **The health checks conducted by GKE for your application servers (Incorrect)**: These checks monitor server health but do not assess end-to-end performance necessary to detect broader network or configuration issues.

Author: LeetQuiz Editorial Team