PCA (Prometheus Certified Associate) sample exam question with answer 120

Question:
What configuration is used to effectively disable grouping of alerts for a particular Alertmanager route?

1. disable_grouping: true
2. group_by: ['*']
3. group_by: ['...']
4. enable_grouping: false

Answer:
C - correct one. Check route
A, D - there is no such configuration option
B - incorrect, the actual syntax for grouping by everything (effectively disabling grouping) is ...