PCA (Prometheus Certified Associate) sample exam question with answer 201

Question:
Which of the following is the definition of a time series?

1. A prediction of the future value of a metric
2. Structured textual data regarding an event
3. A numeric measurement recorded over time
4. A numeric measurement

Answer:
C - is the correct answer, what are metrics
A - while predictions can be made based on time series data, the definition of time series does not include a requirement for predictions
B - this is the definition of a log
D - this is the definition of a metric