PCA (Prometheus Certified Associate) sample exam question with answer 203

Question:
For a histogram metric, what are the different submetrics?

1. _total, _sum, _bucket
2. _bucket
3. _count, _bucket, _sum
4. _count, _bucket

Answer:
C - is the correct answer. Histogram metrics have 3 submetrics: count: total number of observations, sum: sum of all observations, bucket: number of observations for a specific bucket