The correct options are PodDisruptionBudget and StatefulSet using a persistent volume claim.

A StatefulSet using a persistent volume claim gives each pod a stable identity and a stable, dedicated PVC binding. When you use a PVC with an access mode such as ReadWriteOnce and run a single replica the volume can only be mounted read write by one node and that enforces single writer semantics. The stable naming and stable volume binding of a StatefulSet also prevents PVC ownership from moving unexpectedly between interchangeable pods.

A PodDisruptionBudget complements the StatefulSet and PVC access mode by protecting the writer pod from voluntary disruptions during maintenance. A PDB prevents evictions that could create a window where another pod might try to start and compete for the volume, and that helps maintain the single writer guarantee during cluster operations.

Deployment with a persistent volume claim is incorrect because Deployments treat pods as interchangeable replicas and do not provide stable, per-pod PVC bindings. That means a Deployment can more easily lead to multiple pods attempting to mount or contend for storage or to PVC to pod mismatches.

NetworkPolicy to limit access is incorrect because NetworkPolicy controls network traffic only. It cannot prevent multiple pods or nodes from mounting the same persistent volume and it does not enforce storage access modes or pod identity.

DaemonSet with a persistent volume claim is incorrect because a DaemonSet runs a pod on every node and would therefore try to mount the volume on many nodes. That behavior conflicts with single writer requirements and is not appropriate for a single instance database.

Full AWS Practitioner Certification Question