A compute workload has a steady baseline and large interruptible batch peaks. Checkpoints allow interrupted tasks to resume. Which purchasing strategy best balances cost and reliability?

1. Use only one Spot instance type in one AZ and remove checkpoints.
2. Purchase a fixed commitment sized to the largest rare peak without utilization analysis.
3. Use Spot for the only noncheckpointed critical database and assume interruptions cannot occur.
4. Use commitments for the suitable steady baseline and diversified Spot capacity for checkpointed batch peaks.