Which Amazon EC2 purchasing option will meet these requirements MOST cost-effectively?

Explanations:

On-Demand Instances are charged at a fixed rate per hour or second, depending on the instance type, making them suitable for applications that require flexibility. However, they are not the most cost-effective option for non-continuous workloads, as costs can accumulate quickly.

Dedicated Instances run on hardware dedicated to a single customer. They provide greater isolation but come at a higher cost than On-Demand or Spot Instances, making them unsuitable for cost-sensitive, intermittent workloads.

Spot Instances allow users to bid on unused EC2 capacity at potentially lower prices than On-Demand instances. This makes them the most cost-effective option for applications that can tolerate interruptions, as they can be significantly cheaper for non-continuous workloads.

Reserved Instances provide a significant discount (up to 75%) compared to On-Demand pricing but require a commitment for a one- or three-year term. They are not ideal for test environments where the workload is intermittent and does not require continuous operation.