PCA (Prometheus Certified Associate) sample exam question with answer 220

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: http-api-errors
env: prod
service: api
severity: medium

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

Answer:
D - is the correct answer. Since none of the child routes of the root route match, the root route (associated with the a-team-email receiver) is used