You have an Azure Databricks workspace that contains multiple all-purpose clusters.

The correct answer is D — configure automatic termination.

The problem is specific: clusters sit idle after users finish working but nobody manually shuts them down. Automatic termination solves this directly — once a cluster has been idle for the configured period (no running commands, no attached notebooks with active execution), it shuts itself down. You eliminate the idle cost without any manual intervention and without affecting any workload that is actually running.

Option A (convert to job clusters) would force users off interactive all-purpose clusters, disrupting their development workflow. Option B (spot instances) reduces the hourly rate while a cluster is running but does nothing about the idle-time problem — a cheaper idle cluster is still waste. Option C (enable autoscaling) reduces the number of workers during light load but keeps the cluster alive at the minimum node count. It saves some cost but doesn ' t fully eliminate idle spend the way auto-termination does.