PCA (Prometheus Certified Associate) sample exam question with answer 99

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: test
service: db
severity: low

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

Answer:
C - is the correct answer. More info at route
A - b-team-page is incorrect as the given alert has env="test", not prod. Since the route associated with b-team-page failed to be matched, the alert is routed to the receiver designated by the parent route.
B - a-team-email is incorrect as it is associated with the default (root) route. Since the given alert matches the route corresponding to the b-team-email receiver, it never falls back to the default route.
D - a-team-page is incorrect as the given alert has severity="low", not high or critical as necessitated by the first a-team-page route. Additionally, since the given alert matches the route corresponding to the b-team-email receiver, it never reaches the next route associated with the a-team-page receiver