PCA (Prometheus Certified Associate) sample exam question with answer 450

Question:
Which of the following PromQL functions are used for filtering time series?

1. by()
2. without()
3. on()
4. ignoring()

Answer:
A, B, D - are correct answers. by(), without(), and ignoring() functions are used for filtering time series based on labels
C - incorrect. on() function is used to join time series based on matching label sets