PCA (Prometheus Certified Associate) sample exam question with answer 472

Question:
Which of the following is a valid Prometheus alerting rule expression?

1. up > 0.9
2. rate(up[5m]) < 0.5
3. max_over_time(up[5m]) > 0.9
4. histogram_quantile(0.99, sum(rate(request_duration_seconds_bucket[5m])) by (le)) > 1

Answer:
D - is correct. This is a valid Prometheus alerting rule expression that triggers an alert if the 99th percentile of the request duration metric exceeds 1 second