PCA (Prometheus Certified Associate) sample exam question with answer 320

Question:
Which of the following is a valid Prometheus query language expression?

1. avg(up{job="prometheus"})
2. up{job="prometheus"} | rate
3. max_over_time(up{job="prometheus"}[5m])
4. up{job="prometheus"} > 0.5

Answer:
C - is a valid Prometheus query language expression that calculates the maximum value of the up metric over the last 5 minutes for targets with the job="prometheus" label