Which Azure feature could have prevented accidental deletion of critical resources?

Resource Locks prevent accidental deletion or modification of Azure resources. They can be applied at the subscription, resource group, or individual resource level, and can be set to either "CanNotDelete" or "ReadOnly". This directly addresses the problem of accidental deletion. Azure Policy helps enforce organizational standards and assess compliance, but it doesn't directly prevent deletion once a resource is created. Management groups help organize subscriptions and apply governance at scale, but they don't offer direct protection against resource deletion. Azure Monitor collects and analyzes telemetry data, providing insights into resource performance and health, but it does not prevent resource actions like deletion.