PCA (Prometheus Certified Associate) sample exam question with answer 235

Question:
What is a Prometheus annotation?

1. Metadata that uniquely identifies an alert
2. Metadata used to expose identifying information about targets discovered via various service discovery mechanisms
3. Metadata that provides longer-form information about an alert
4. Metadata that uniquely identifies a time series

Answer:
C - is the correct answer, check defining alerting rules
A - is incorrect as labels uniquely identify an alert
B - these are known as meta labels, not annotations
D - the metric name and labels uniquely identify a time series