PCA (Prometheus Certified Associate) sample exam question with answer 207

Question:
What type of metric is BEST for representing the memory used on a server?

1. Summary
2. Info
3. Gauge
4. Counter

Answer:
C - is the correct answer
A - summary metrics sample observations and there is no need for such sampling in this scenario
B - this is not a valid type of Prometheus metric
D - is incorrect as the memory used on a server can go up and down arbitrarily while counters can only store monotonically increasing values