PCA (Prometheus Certified Associate) sample exam question with answer 506

Question:
What are the three principal components of the Prometheus exposition format?

1. Metric name, sample values
2. There are not three components, only the samples are exposed
3. Metric type, metric name, metric value
4. Metric type, help text, one or more samples

Answer:
D - is the correct answer. More at exposition_formats
A - is incorrect as this answer is missing the metric type and help text which are principal components
B - is incorrect as the exposition format includes help text, metric type and one or more samples for each exposed metric
C - is incorrect as there can be multiple time series samples associated with a particular metric name and type, not just a single value. Additionally, help text is a principal component of the exposition format that is missing from this answer