You have an application running in Google Kubernetes Engine. The application invokes multiple services per request but responds too slowly. You need to identify which downstream service or services are causing the delay. What should you do?

A. Analyze VPC flow logs along the path of the request. B. Investigate the Liveness and Readiness probes for each service. C. Create a Dataflow pipeline to analyze service metrics in real time. D. Use a distributed tracing framework such as OpenTelemetry or Stackdriver Trace.