What is the MOST cost-effective EC2 instance purchasing option to meet these requirements?

Explanations:

Reserved Instances are a cost-effective option for long-term, steady-state workloads where instances are used continuously over a one or three-year term. They are not suitable for batch workloads that only run for short periods and can be interrupted.

Spot Instances are the most cost-effective choice for workloads that can tolerate interruptions. They allow users to bid on unused EC2 capacity at significantly lower prices compared to On-Demand Instances. Since the workloads can resume from where they left off, Spot Instances are ideal.

Dedicated Instances provide physical servers dedicated to a single customer but are generally more expensive than On-Demand or Spot Instances. They are not designed for cost-effective, short-term batch workloads, especially those that can handle interruptions.

On-Demand Instances allow users to pay for compute capacity by the hour with no long-term commitments. While they offer flexibility, they are typically more expensive than Spot Instances for batch workloads that can handle interruptions and are not the most cost-effective option.