PCA (Prometheus Certified Associate) sample exam question with answer 518

Question:
What is the function of the for attribute in a Prometheus alerting rule?

1. Specify the thrashing window and threshold that determine when to stop firing alerts when the expression has recently oscillated between true and false
2. Specify how many series must satisfy the expression to fire an alert
3. Specify how long the expression must be true before an alert is fired
4. Specify the time range over which samples are considered for the alerting expression

Answer:
C - is the correct answer. More at defining-alerting-rules
A - is incorrect as there is no alerting rule attribute that provides such a behavior
B - is incorrect as one alert will be fired for each result generated by the query expression
D - is incorrect as this is determined by any range selectors in the query expression