What should a solutions architect do to meet these requirements?

Explanations:

Spot Instances in an EC2 Auto Scaling group can help reduce costs, but EC2 Auto Scaling groups require more management overhead and are not the most efficient solution for containerized workloads compared to managed services like EKS.

Spot Instances in an Amazon EKS managed node group provide the lowest cost option for running stateless containerized applications that can tolerate interruptions, while EKS handles much of the operational overhead.

On-Demand Instances in an EC2 Auto Scaling group do not provide cost optimization. They are more expensive compared to Spot Instances and require more operational management than EKS.

On-Demand Instances in Amazon EKS managed node groups would increase costs compared to using Spot Instances, and while EKS reduces operational overhead, the cost is higher than necessary for stateless applications that can tolerate disruptions.