PCA (Prometheus Certified Associate) sample exam question with answer 248

Question:
What does the following metric_relabel_config do?

scrape_configs:
  - job_name: example
    metric_relabel_configs:
      - source_labels: [__name__]
        regex: database_errors_total
        action: replace
        target_label: __name__
        replacement: database_failures_total

1. tells prometheus to only scrape targets with the metric database_errors_total
2. drops metric with the name `database_errors_total
3. merges the metrics database_errors_total and database_failures_total
4. renames the metric database_errors_total to database_failures_total

Answer:
D - correct answer