To identify the slowest endpoint, you should sort by a tail latency metric. The p99 latency column represents the response time for the 99th percentile of requests, meaning only 1% of requests are slower. Sorting by p99 latency effectively highlights the endpoints that deliver the worst performance to a segment of users, which is the standard method for finding the "slowest" endpoints that require optimization.

B. Sorting by requests shows the most frequently used endpoints (throughput), not the slowest ones in terms of duration.

C. Total time is a cumulative metric (average latency × request count). A fast but high-traffic endpoint can have a high total time.

E. Error rate measures reliability and the frequency of failed requests, not the duration of successful requests.

1. Datadog Documentation, "Service Page". The documentation describes the Resources tab on the Service Page, which lists all endpoints. It details the available columns for sorting, including latency percentiles like p99, to investigate performance bottlenecks.

2. Datadog Documentation, "Key APM Metrics". This page defines core APM metrics, explaining that p99 latency is a crucial indicator for identifying poor user experience and slow performance.