What should a solutions architect do to meet these requirements?

Explanations:

Spot Instances in an EC2 Auto Scaling group can be cost-effective, but managing the container orchestration manually would increase operational overhead. Using a managed service like Amazon EKS would minimize overhead.

Spot Instances in an Amazon EKS managed node group provide cost savings while leveraging EKS for container orchestration. EKS handles scaling and management, and Spot Instances work well for stateless, disruption-tolerant applications.

On-Demand Instances in an EC2 Auto Scaling group would be more expensive than Spot Instances, and using EC2 directly would increase operational overhead without the benefits of a managed Kubernetes service like EKS.

On-Demand Instances in an EKS managed node group would meet the requirements but would be more costly than using Spot Instances, which is the primary cost-saving strategy.