PCA (Prometheus Certified Associate) sample exam question with answer 114

Question:
What is the difference between the rate and irate query functions?

1. There is no difference between the two functions
2. The rate function calculates an instantaneous rate, the irate function calculates an average rate
3. The rate function considers the entire range selector interval, irate only considers the last two samples in the range selector interval
4. There is no such function called irate

Answer:
C - rate and irate