PCA (Prometheus Certified Associate) sample exam question with answer 560

Question:
Consider the following Alertmanager routing configuration.

route:
  receiver: a-team-email
  routes:
    - receiver: a-team-page
      matchers:
        - severity=~"high|critical"
    - receiver: b-team-email
      matchers:
        - service="db"
      routes:
        - receiver: b-team-page
          matchers:
            - env="prod"
    - receiver: a-team-page
      matchers:
        - service="db"
        - env="prod"

Given an alert with the following labels, to which receiver will the alert be routed?

alertname: database-down
env: prod
service: db
severity: high

1. b-team-page
2. b-team-email
3. a-team-email
4. a-team-page

Answer:
D - is the correct answer
A, B - are incorrect as these receivers are never reached because the alert matches the prior route associated with the a-team-page receiver
C - is incorrect as this receiver is associated with the default route which is never reached because the alert matches the route associated with the a-team-page receiver. Remember, the default (root) route is only used if none of its children are matched