The immutable: true field is supported byConfigMap(and also by Secrets, though Secret is not in the options), soCis correct. When a ConfigMap is marked immutable, its data can no longer be changed after creation. This is useful for protecting configuration from accidental modification and for improving cluster performance by reducing watch/update churn on frequently referenced configuration objects.

In Kubernetes, ConfigMaps store non-sensitive configuration as key-value pairs. They can be consumed by Pods as environment variables, command-line arguments, or mounted files in volumes. Without immutability, ConfigMap updates can trigger complex runtime behaviors: for example, file-mounted ConfigMap updates can eventually reflect in the volume (with some delay), but environment variables do not update automatically in running Pods. This can cause confusion and configuration drift between expected and actual behavior. Marking a ConfigMap immutable makes the configuration stable and encourages explicit rollout strategies (create a new ConfigMap with a new name and update the Pod template), which is generally more reliable for production delivery.

Why the other options are wrong: Deployments, Pods, and ReplicaSets do not use an immutable: true field as a standard top-level toggle in their API schema for the purpose described. These objects can be updated through the normal API mechanisms, and their updates are part of typical lifecycle operations (rolling updates, scaling, etc.). The immutability concept exists in Kubernetes, but the specific immutable boolean in this context is a recognized field for ConfigMap (and Secret) objects.

Operationally, immutable ConfigMaps help enforce safer practices: instead of editing live configuration in place, teams adopt versioned configuration artifacts and controlled rollouts via Deployments. This fits cloud-native principles of repeatability and reducing accidental production changes.

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