The requirements explicitly identify two separate environments: a production ACK cluster using stable pay-as-you-go ECS capacity and a dedicated development cluster that is used only intermittently. Option D satisfies both requirements while preserving ACK-managed node-pool operations.

For the development cluster, preemptible instances—now generally described as spot instances in current Alibaba Cloud documentation—are appropriate because the workload is temporary, interruption-tolerant, and cost-sensitive. Alibaba Cloud states that spot capacity can reduce compute costs substantially compared with ordinary pay-as-you-go instances. ACK node pools can use spot instances and can automatically perform scaling and replacement operations.

The production cluster remains on pay-as-you-go nodes, avoiding the reclamation risk associated with spot capacity. A separate managed development cluster also preserves workload isolation.

Option A does not provide the required second development cluster and imposes subscription commitment. Option B requires Eric to maintain an external Auto Scaling and bootstrap mechanism, contradicting the desire for ACK to manage nodes. Option C again describes only one cluster and fails to retain the required production environment.

Study Guide reference: Core Infrastructure Deep Dive — ACK managed clusters, node pools, spot/preemptible ECS, and cloud cost optimization.