An EC2 CodeDeploy release increases errors after traffic reaches the new revision. Operations needs automatic mitigation and a usable prior release. Which practices support this? Select 2 answers.

1. Assume a code rollback reverses every external transaction automatically.
2. Delete all previous revisions before observing the new application.
3. Disable error alarms so the deployment appears successful.
4. Retain the prior compatible revision and account for state changes that a code rollback cannot undo automatically.
5. Configure relevant alarms and automatic rollback for the deployment group.