PCA (Prometheus Certified Associate) sample exam question with answer 390

Question:
Assuming the current epoch time is 1666150830, which of the following queries yields the value of the up metric at 1666150330, no matter when it is evaluated?

1. up @ 1666150330
2. up offset 5m
3. up{timestamp="1666150330"}
4. up[5m]

Answer:
A - is the correct answer
B - is incorrect as this query returns the value of the up metric exactly five minutes prior to when the query is executed. As time passes, the execution time will be more than five minutes offset from the desired timestamp (1666150330)
C - incorrect as it is the @ modifier that allows querying the value of a metric at a specific timestamp, not a label
D - is incorrect as this query returns all values of the up metric in between when the query is evaluated and five minutes prior